While having the muffler replaced on my 1991 300E, I mentioned to the mechanic that the car idles rough when at a stop with the car in gear and the AC on. If I turn off the AC it smoothes right out. No problem with acceleration or while cruising. He tested the ICV and said that there is no power going to it and that it may be a wire, harness, or pod issue and that it may cost from $100 to $1000 to diagnose and fix.

Does this sound right? Anything I can check before I sink $$ into it?
Idaes?

Nick