I cleaned the throttle body and the ICM. Afterward at first the idle was so low (400 rpm), that I ran the screw up to increase the idle speed to about 750 rpm. All was well for a couple of days, then all at once it started to idle at approx 4000 rpm and wouldn't go down any. I then loosened the screw back all the way down and finally reduced the idle to approx 1500 rpm. Next day it was idling up one minute then down the next. I took it to a mechanic and he diagnosed it with a faulty temp sensor (says it was reading -22F). He replaced it and then told me the TPS was not functioning properly!

Ok, that was the history. Now, I have a TPS and throttle body from an '89 240 ... can these be interchanged?

Long post, sorry. This thing is driving me nuts ... and breaking me too! :-)