I have a 1993 Deville. The engine surges very fast at idle when the engine gets hot. I already replaced the Throttle pos sensor because of E27, E55 and E85. The errors are gone but the engine still revs very high at idle sometimes. If I put the car in nuetral and tap the gas the idle drops back down to normal. Does this sound like the idle speed control valve is sticking? How can I test it? What else can cause the engine to rev up very high at idle?
Thanks in advance,