ok i got a 93 940 turbo wagon (ya baby)... toexplain my problem let me start at the begining...i was getting a rough cold start a while back and the car was running rich. i found that my intake manifold gasket was just about hanging off at 4 cylinder which was giving me a bad vacum leak... explains that problem... so i change it and bolt everything back up and click click vroom!!! no more rough start, but the car held an idle at about 4000 rpm. so i though ok the comp needs to recalibrate so i allowed it to run for a little while and, as i thought, the car idled downbut stalled out... so i started it again and it constantly varied in idle from bout 500rpm to 2500 rpm while getting a ping near my exhaust manifold at the 500's... i towed it to the local european garage whos owner has a volvo ironicly and they told me that my idle air control valve was bad... so i changed it and it still does the same thing... so far i have dropped about $400 and i just want to get my car back on the road... could anyone PLEASE help me???

 

Is there a chance you swapped the plugs for the idle motor and the TPS?
Also did you mess with the Idle adjustment?

 

no the only thing that i disconnected was the IAC hose at the manifold and that was only to get to two of the mounting bolts for the manifold....

 

Maybe another Vaccum leak.
Have you checked for that using Carb cleaner with the engine running?