Sitting at a red light or in my drive way my 97 A6 wants to stall out. It has stalled in the past, but most of the time the RPM's drop below 200 then come back up to about 800 and normal idle. Over the summer I had a throttle position sensor CEL, but lately I have not seen any CEL's. Any ideas or past experiences? Could a TPS cause this, where is it located, and how much does it cost?

Thanks everyone

i'm not sure if that's your problem ....take the ICV (idle control valve)out and clean it...see if it changes anything.... check for bad wires or plugs....
other than that i relly don't know......EGR valve? vacuum leak?
no idea! hope this helps!

My guess is that it's a vacuum leak. I would suggest you remove everything you can leading from and into the throttle body and clean it with a spray can carb cleaner or throttle body cleaner. Pay attention to look for and note any oily surfaces. On the way, take a look at every vacuum connection and bend the hoses around to see if any of them are dry rot or cracked. You'll probably find a couple "suspects". It only takes a small leak to wreck your idle.

Ed

It's simple to take off and easy to clean...i just sprayed WD-40 in and shook it up a few times...cleans and lubricates....now my idle is perfect