1983 928S idling problem
 

The symptoms are that sometimes (but not always) when I stop the car with the automatic tranny in the Drive position the idle will drop very low and sometimes kill the engine. This happens when the engine is up to operating temperature. I suspect a vacuum leak somewhere, although I would think a vacuum leak would not cause a periodic problem, but rather all the time. I plan to replace the intake manifold rubber sleeves and various other hoses that might be the source of a vacuum leak. A key question I have is whether the 1983 928S has an idle stabilizer that I need to pay attention to. I am a new registrant; this is my first submission.

Check the switches on the throttle, could be car doesn't know its in "idle" mode. Getting rid of all the vacuum leaks will be a big help too.

Early cars have a dumb device that prevents extreme vacuum, but doesn't do anything for idle, called a vacuum limiter. They also have a AUX air valve on the cross brace that I think kicks in for AC and maybe cold operation at idle.

I'd also check the temp sensor.