87 TBI Idle problem 87 454

[esbstuff]

My truck started this weird problem last week and I can't figure out what it is...

It will start and idle fine. But after awhile it will idle alittle slower, then alittle faster. Starting out just as a 100 rpm diff and finally going from stall to 1K rpm. If I shut the truck off and restart it will idle fine for 1-20 minutes and then start acting funny again. It will do this on either tank. And I can't make it do it and it has a hit or miss check engine light, but by the time I read it, the it shows no codes. Occasionally I will feel the truck surging while I am driving down the road or want to die at a light. The only constant is when it is acting funny, the exhaust will smell rich. I should say the TBI was replaced with a later unit (90) and the approperate jumper harness was used. The problem did not surface till 30-40 days after the change.

The following items have been replaced since the problem begain.. vacumn hoses, egr valve, fuel filter, one fuel pump all with no change.

The following have been replaced in the last 3 months complete tbi, intake gaskets, timing change, cam, tbi gasket, cap, rotor plugs, wires, o2 sensor, water sensor. All the parts were replaced with GM, AC or very good aftermarket...

Thanks in advance... Eric

[esbstuff]

I finally figured out the problem... map sensor. A new one cured the problem.