[dme]

I've just solved a similar idle problem with my 951. My biggest mistake was not checking some of the simple things on my car first and just assuming it was the Idle control valve (ICV). I replaced the ICV because of erratic idle. It didn't help. Finally, I took the throttle body off the car for inspection. I had a hunch the throttle position switch (TPS) was bad because the injectors were not shutting off at deceleration. I could hear the switch in the TPS click when the throttle was closed and assumed it was working. Well, it wasn't. I took the TPS apart and cleaned it out though it really wasn't dirty. For whatever reason, it started working again. While examining the throttle body I discovered that it was not closing all the way and it was not hitting the set screw stop. Turns out the TPS was misaligned and the micro switch in the TPS was acting as a stop. I readjusted the TPS and the stop screw, put it all back together and so far, it seems to be working correctly.
I've had this car for three years and should have verified the throttle body operation before this, but I looked passed it while working on other parts. My mantra is start simple and cheap and move up from there. I failed on this one.