after a very expensive tuneup, my 400E now runs again, (see my "my 400E is going nuts" post for details) but the idle surge problem is back and getting worse. it only happens in "D" and "R" and only at idle or near-idle RPMs. sometimes at a red light the car bucks against the brakes so much i have to shift it to neutral -- and when i do, the idle smooths out... shift it back to "D" and it starts bucking again.
what does this sound like, diagnostically? why would having the car in "N" vs "D" have anything to do with it???
what does this sound like, diagnostically? why would having the car in "N" vs "D" have anything to do with it???