I have been chasing this High Idle After Warm Up since Feb. 2005. Yes it's been a long time but finally solved. I even waited 2 weeks before posting to make sure it was really fixed.
First of all I want to thank everyone that along the way have replied with possible fixes and you got to know I tried them all. At times I just said screw it and set the idle at the point when the idle was running high between 1100 and 1200 RPMs and dropping it to 900 RPMs. I left it there to the point I didn't think about it until I tried to set base idle again.And the game was on again.
Of course going threw all the testing,cleaning and double checking and coming up with ZIP. So 2 weeks ago I was looking at the fuel distributor and decided to pull it off and pull the plunger out to clean while spraying Throttle Body Cleaner up into the fuel distributor a lot of gunk came out. I let it soak for a while and sprayed it until it was clean.
I still can't believe that was the problem all along.I couldn't find anything in the Bentley Man. that would indicate that this could cause the high idle problem that I was having. I just wanted to post this in case someone else was having this same problem and now this can be added to the list of possible causes. Now all I have to do is wait for the next problem and hope it doesn't take as long to solve. Charlie