My '88 535ia is running real rough at idle 90% of the time. When i was getting the A/C worked on, I agreed to get a tune-up. My mechanic said that he would have to do a tune-up as a starting place for finding the problem. i agreed. Well, 150.00 later and the idle is still rough. They couldn't find the problem. They checked for vaccuum leaks, checked the idler control valve, and the airflow stuff. The car seems to be running rich at idle, but fine otherwise.
Also, I still have an electric demon in the car. I checked the two grounds. I removed them and cleaned the contacts, but no change.