Hello all! This is my first post with you so forgive me if im a bit long winded but I am desperate for some help here. I have a 1992 Jimmy 4x4 with the 4.3 vortec. The car has 200k on it but the engine has only 30k.

Several months ago I was having an acceleration issue. After the engine was warmed up, whenever I would stomp on the gas, like going up a hill or pulling out into traffic, the engine would hesitate or buck 3-4 times until it got to 2nd gear then it would be fine. When I spoke to my mechanic about it he looked at the electronics and replaced the whole distributor with a new cap n rotor. No help. I was told the only other problem could be the computer. So I swapped it and, you guessed it. No help. I was tired of throwing $$ at it and it was such a small issue most of the time so I let it go. No issues AT ALL with normal acceleration. It started and ran fine all other times. That was 6 months ago.

Fast forward to this month. It has started to idle very rough. Exhaust stinks real bad. Check engine light comes on after a while. I put a new spider in and NO change. Back to the mechanic where he went stem to stern over the fuel system. New fuel pump, fuel filter, Fuel pressure was checked. Exhaust was pretty new but they pulled it and ran it w/out exhaust. Vacuum issues were looked at. The code said EGR but that has been replaced with NO effect. Codes were cleared and it has not come back but it still runs like crap. Oh and when it is idling like crap, I lose the brake pedal.

Plenum has been pulled several times, vacuum lines checked several times. Its had new plugs and plug wires. Ran it with a new coil and replaced the O2 sensors. I have had it at 2 different shops and no less than 5 mechanics have been over it and cannot find the problem. I am at the end of my rope. I cant afford to keep throwing cash away on it. If I cant get a solution soon, she is going to the yard for scrap and I will buy a newer one. What a waste because of the new engine and all the stuff I have done to it!!

So here is the question. What allows this truck to start fine, run fine, idle fine and accelerate fine for the first 10 minutes of running. Then after its warmed up, it wont accelerate correctly or idle correctly. Are these two issues related or completely different problems?

I would be greatly in debt to anyone that can help me out here. Thanks!

 

Check the vacume line coming off the brake booster and trace to where it connects on the engine.Look for a loose connection replace the clamps if neccasary.