1995 Chevy S10 4.3 V6 TBI VIN Z engine 238k miles.
If anyone remembers I had my engine replaced with a used one little over a year ago. I had engine stumbling with light throttle just off of idle. The engine had a coolant leak internally and the EGR was sticking according to the mechanic. He just cleaned the EGR valve then but I replaced it later.
Anyway, I started getting similar problems again last week. The engine was shaking and stumbling when I give it throttle from idle. It was idling fine and would smooth out at higher rpm, maybe less power though.
So today I was out checking the EGR valve again. Took it out, put it back, then I started checking the vacuum hoses off the EGR solenoid.
I put my finger over one of the hose ends or maybe the vent, not even sure. Then I get a hissing sound from the throttle and the engine idle drops and it starts stumbling really bad. Connected the hoses back and it’s still hissing and idling terrible.
Turned engine off and it has a little smoke coming from the IAC valve area inside the throttle. I went and bought a new IAC valve, installed and it’s still the same. Noticeable hissing from throttle, I think it’s coming from the valve port area. Hiss is hard to hear with the air cleaner back on. Always has a little smoke coming off the valve port area when I shut the engine off.
I’ve never taken the throttle body off, I’m not sure what to be looking at now. Maybe the valve isn’t getting a signal or I have an air leak somewhere else. Does anybody have suggestions? Thanks.