Fluctuating Idle with Rotten Egg smell.

[mikmic2]

I've got a 1992 Cutlass Ciera with a 3100. It idles up and down just like you would expect with a vacuum leak. However, I can't seem to find any leaks. I've checked the vacuum booster, and just about every other line I could see, but they aren't leakig. It also has a moderate Rotten egg smell. I thought of the Catalytic Converter, but it runs good going down the road.

Anybody have any similiar experience, or have a clue what it might be?

I thought maybe the EGR valve. Does that sound possible?

Any other ideas?

[s10blazerman4x4]

From my experiences last few weeks in my cutlass calais 2.5 it was two things: O2 sensor and that should throw a code and the catalytic converter went out along with an exhaust leak at the manifold. Take in mind i got FWD but check everything for leaks and check for codes.

[Slade901]

If the IDLE goes up and down by itself, it sounds like a bad TPS (Throttle Position Sensor) going bad. I would also try to clean the IAC (Idle Air Control solenoid). They are all located on the Throttle body. It might be a good time to remove the egr and it's pipe and clean it as it maybe clogged up with hardened carbon.