Thought this might be able to help you guys. My 945T (94 - 99k) has been having high/low idle problems - it wanted to idle around 400 or 1500+ - there was no middle ground adjustment I could make to the idle screw. I cleaned the throttle body, replaced tune up items, replaced ICC (idle control solenoid - silver ‘cannister’ under throttle body) with no success. I scoured the faq for several months trying to find the cure on my own, with no luck. Thankfully, per Steve Ringlee’s suggestion to check and/or replace the TPS (Throttle position switch) - which turned out was in the faq all along - now things seem to be just fine. I replaced the TPS.

What was happenening is when I adjusted the idle screw, I could find a ‘sweet’ spot where the car would idle around 1000 rpms - which was great - as all I had been seeing was 400 or 1500+ rpms. However, as soon as I shut the car off and started her back up, the idle would be crazy low or crazy high again. Basically, I have been living with a 1500+ rpm idle speed for months now - which is no fun with your wife constantly griping at you for riding too close to the guy in front of you’s bumper! (“I’m coasting!!! Look. No feet!!!”).

Anyway, as I didn’t have access to my PC when I replaced the TPS, I did a seat of pants installation - which worked and is what I wanted to tell you guys. I still haven’t read the faq since my fix, but I know my install method was goofy. Here goes - I pulled the throttle body, unplugged and unbolted the TPS - noting where the old switch was positioned. Replaced the switch and bolted it all back up (I had remembered the faq saying something about listening for a ‘click’ and making sure things were perfect, but I was in a hurry and couldn’t access the brickboard.) Cranked up the engine and again, idle problems. So I decided to adjust the positioning of the TPS with it bolted to the throttle body. It’s done with an allen wrench - and is definitely a tight fit for the far allen screw. With a few adjustment attempts (you can slightly twist the TPS on it’s mount by loosening the allen screws), and shutting off/on the engine and readjusting the idle screw, I FINALLY have a decent idle. And have had it for three days. BTW, I also replaced the FPR (fuel pressure regulator - bolts on the front of the fuel rail) but don’t think this made any difference in idle.

Now, if I can only figure out why my mileage has dropped to around 17.5 mpg and my performance is down. That is another post for another day I guess! But am open for suggestions.

Hope this helped.