Bad parts
I'd get a scanner and see what the IAC counts are after I cleaned up the TB by removing the IAC. IAC housing, TB top plate, clean all passages and reassemble with fresh gaskets.
One would think so. In fact 2 experienced MB techs did. Results don't lie. Reading immediately went up by 0.2 volts and upstream warning went off? It doesn't influence the fuel mixture but it might inform the ECM in ways we don't understand
I replaced the upstream passenger side with a Walker brand, it is about mid price. The least expensive is the Denso, and most expensive is AC Delco. I've heard stay away from the Bosch, but not sure about the others
Well, as I mentioned before, I bought a (cheap) ICM from 1Aauto for $23.95, and it was defective. Started the car, and it would idle pretty good, but would not go over 2K rpm, and would miss and totally crap out. When starting, at end of cranking, just before starting, it would kinda kick back, way too far advanced with timing. Put the old one back on, and would start and run o.k. 1Aauto refunded my money for the ICM as well as for a (cheap) MAP sensor I didn't bother to install. They told me not to bother returning the parts, just throw them away. Anyway, I didn't know that an ICM would cause a symptom like that.
So, I ordered another ICM from Rock Auto, a Delphi, and it arrived today. Paid $63 for it----MADE IN CHINA



