cant go over 45

Ok so I have a 78 caprice classic wagon 350. I just got it and there's a problem. It starts fine idles fine and drives pretty good as well. However, once I try to go past 45 or 50 the car doesn't wanna go any faster it kinda chugs along and if I try to go faster it shuts off leaving me stranded. But the car will most of the time start right back up. The guy I bought it from says the ignition control module is overheating or the kickdown cable needs to be adjusted any help would be greatly appreciated

Does it happen when you are accelerating to say 45-50 or cruising over 45-50? No other acceleration issues

below 45? Have you checked your plugs(Are they black ,brown,white etc?) ? Any feeling of slipping when you get

over 45?

Accelerating to 45-50 is normal but once I hit around 45-50 it starts to hesitate and starts to chug along. It won't go any faster if I step on the gas pedal to try and go faster it stalls and shuts off

And no I haven't checked my plugs. And as for slipping in not really feeling any slipping. The engine wont rev up when I'm at 45-50

I'd check your plugs for anything irregular it does sound like a high rpm issue that maybe the ignition module ,

they are not expensive you can usually replace the module ,the distributor cap and rotor for 50-60 dollars.

it could be the icm (igniton contol module) when i starts to go out once it gets to hot it stops working sometimes will die right there or may cool off and start again.
It takes 5 mins to replace 
good sized phillips screwdriver magnetic tip preferable
*remove cap 4 hold down clamps (place to the side no need to remove)
*remove rotor 2 screws
*remove 2 screws holding down the icm unplug electrical connections at both ends 
*replace icm put fresh di electric grease under it and the the terminals 
*snug the screws and a light turn more 
*replace rotor & cap 
*start the car

i recommend you get the mid level or higher at the parts store 
i got the 20$ one died 2 months later the guy messed up on the warranty exchange and gave me the $35 one and idled cleaner and can hear the heartbeat/burbbling of the motor more ..oh and she hauls ass more
If you got the dough to spend for $100 you can grab the pertronix flamethrower coil&icm im sure that would put a pep in your step

if its the kickdown adjustment on my 77 th200(had thought it was a th350)
*driver side of the car theres a black cable running through a bracket bolted to the rear part of the drivers side intake manifold.
*Just INFRONT of the bracket on the cable theres a black plastic housing push underneath it a little clip pops out and releases tension 
*NOW (part i didnt do and had poor results) behind the bracket these another black plastic housing.. squeeze the sides and dismount it from the bracket
*have someone step the gas pedal to the floor 
*with the throttle engaged and seeing tension on the string push down the clip that popped up (infront of bracket)
*once locked plug it back into the bracket
*test drive
i had this issue when i removed the carb to clean and disconnected the cable 
thing wouldnt shift till 4000 or so ..very hard on the tranny ...butthole got tight with every shift lol 
but now all is right 

BUT  now i think of it seems like a carburetor issue your having
Drive it till its warmed up real good and the park pempve the air cleaner and see if your secondaries(rear flaps on carburetor) they should be open ..that may be your issue since it seems like the car stalls or bogs out maybe not enough air and too much gas 
Do you get excessive gas fumes?

So I replaced the icm. I noticed it doesn't shut down on me when I'm at 45-50 however it still won't go past that I'm think its the kd cable? I noticed its really loose but I'm not sure if its supposed to be like that

its not gonna be super tight fairly loose but should have some tension on the string
did you check the secondary if the flap is open when warmed up 
and when it acts ups does it feel like its bogging

Like its really really loose. can easily disconnect it. There's no tension at all. And as for the secondary flaps were like cracked open. Should they be like that orbshould they be wide open? I'm trying to post a pic but its too big a file it says

it should be tight enough to where you have to slide the carb back to unhook it 
i posted earlier on how to adjust it to see how it preforms
if the car was warmed up and driven already the should be open fully if im not mistakened 
see it there is binding/stuck flap ...it should open and close super easy

Oh ok because I tried to press them down but the flaps wouldn't open more. Would I have to take it apart? It looks really clean I'm not sure if its been rebuilt before

theres ur problem the bushing are probobly shot 
during the rebuild the drill em out larger and insert sleeve bushings to restore to factory spec ...check put national carburetors i was gonna buy one the but retuned my qjet and it runs great

ok ill look into the carb issue. as for the kd cable you mentioned you posted on how to adjust it?
btw thank you very much for your help i appreciate it!

its in the first post i made on this thread in the middle of it 
and no problem man just love to keep a chevy rollin
also dont hesitste to post an issue

scy135 wrote:Like its really really loose.  can easily disconnect it. There's no tension at all. And as for the secondary flaps were like cracked open. Should they be like that orbshould they be wide open? I'm trying to post a pic but its too big a file it says

Are you talking about the carb? If yes, they should be closed unless opened by your right foot.
All along it's sounded like a fuel delivery problem to me. Have you checked your fuel pressure?

HeavyChevy77 wrote:it should be tight enough to where you have to slide the carb back to unhook it 
i posted earlier on how to adjust it to see how it preforms
if the car was warmed up and driven already the should be open fully if im not mistakened 
see it there is binding/stuck flap ...it should open and close super easy

the choke, yes. The secondarys, no.

scy135 wrote:Oh ok because I tried to press them down but the flaps wouldn't open more. Would I have to take it apart? It looks really clean I'm not sure if its been rebuilt before

Are you using a Rochester 4bbl carb?
It could simply be an incorrect base gasket causing that. Unbolt the carb, lift it a bit and see if they'll open.

i knew i was off 
the secondary opens as you accelerate at higher speed right 
also good idea with the gasket he said it looks clean

HeavyChevy77 wrote:i knew i was off 
the secondary opens as you accelerate at higher speed right 
also good idea with the gasket he said it looks clean

Depending on the type of carb, yes.
A carb with vacuum secondarys opens at higher rpms as the engine needs more air flow.
A mechanical secondary or "double pumper" type opens at idle as soon as you mash the gas pedal.

Rule of thumb - Auto trans = vacuum secondary. Standard trans = mechanical secondary.
Of course there's always exceptions to the rule, like if you have a high stall speed converter. I'm talking 3500rpm and up.

No ihavent checked my fuel pressure. I probably should though. And yea the choke opens but the secondaries are cracked open. The fuel filter looks a little dirty so ill be replacing that. Ican rev the engine while its sitting but not while im driving

so i finally got around to doing some work on my wagon, with my newborn and wife and all the good stuff that comes with babies. i had to put my car in the back seat for a bit. so this is what ive figured out... i was thinking it has to be a fuel delivery problem i couldn't think of anything that can cause my car not to go over 45-50. so i thought why not start with some basics? i bought a fuel filter because the one it had looked ancient and like it was made of varnish, i thought it might be clogged. (my car has an external fuel filter btw.) so i install the fuel filter no problems. i turn the car on and it started no problem but the filter didn't fill up i thought, wait what? god damn fuel pump must be busted! so i give it some rpms and it still didn't fill up. i checked to see if i put it backwards and no it was on correctly. but i noticed as i fallowed the lines around, that the fuel filter was BEFORE the fuel pump. i thought it was a little odd at first but at the same time no because i do this to a car that's been sitting a while to keep gunk from going into the fuel pump and ultimately the engine. so i crawled under the car and looked at the fuel pump to see if what i noticed was true and it was. BUT, i also noticed the line that goes from the pump to the carb had a freaking kink in it. it wrapped around some smaller hard lines and it restricted fuel flow. so basically i had to redo the fuel lines, because they were dry and brittle, and moved the filter to after the fuel pump. once that was done, i fired it up and the filter filled up quickly. i test drove it for a bit but i couldn't drive it for long because i have no tags for it yet and the wife was pretty upset at me for other reasons. anyways im gonna test drive it some more tomorrow this seemed to have fixed my problem and throttle response is a lot better thats for sure. thank you all for your help and input it was greatly appreciated! =)