95 5.7L (K) TBI with AC. Stutters and surges at low throttle positions. WOT is normal. Sometimes bogs for 1/2 second when throttle is quickly pushed from idle. I tow 8,000# behind the truck and there is never a lack of power (as compared to before the problem.). The problem What i have done so far: The only thing not new in the exhaust is the driver side manifold. Pulled the EGR and cleaned (it was pretty clean when I removed it) Checked the EGR with a hand held vacuum pump and it held open and closed properly. EGR hole in manifold is clean. Coolant level doesn't change and oil consumption is normal for a vehicle with 120K on it. New cap and rotor. Inside of TB below butterflys is spotless. Things I still need to try: IAC and TBI gasket. EGR vac solenoid (what is a good way to test the EGR vac solenoid?). I tried to find an Iac for the 95 Silverado (Google) and have yet to find one. Anyone know of a good online store that has one? This IAC threads in where all of the ones I have found are held in with two srews/bolts. Can I clean the IAC safely? Can it be adjusted, if so how?

Note: This problem started soon after the transmission was rebuilt but I don't belive that work has anything to do with the current problem. Also the intake manifold was resealed 2 years ago for an external oil leak.

This problem seems to be a big one, lots of others with the problem but few solutions.

Any suggestions?

Thanks Mascobe D.

 

Rmoved and cleaned the IAC. Tested: Still has a surge when using the throttle lightly. The bucking has simmered down though. Replaced the spark plugs. No change in operation. The plugs were all alike and had a clean to light tan color which I think is quite normal. Different air filter. No change. Tested the TBI for leaks around TBI/IM gasket: none found. Exhaust (PS manifold/y pipe/cat./3" pipe/muffler/etc.) is all new accept for the driver side manifold. In my mind that leaves the EGR vac solenoid, MAP sensor. Anybody have any ideas?

Mascobe D.

 

I know what you are going through, because it sounds like you were having the same problem i've been fight, and i have replaced just about everything on my truck (92 c2500 350 TBI) and what it turned out to be was something in the PCV valve wasnt working properly it rattled just fine but when i unplugged it with the engine running then put it back in my truck smoothed out after that. Worth a try.