Pontiac Repair: Pontiac Spordic Idle, pontiac transport, vacuum leak

Question
Hi Todd,
I have a 94 Pontiac Transport with a 3.8L engine.  When I start the car, the idle is too high to put into gear without a thump.  After the car warms up, you can tap the gas pedal and the isel  seems to be normal and it goes into gear OK. Even when warm though, the idle seems sporadic as it continually climbs and lowers a little bit.  Is there anything that can be done to adjust it?  Is there some kind of sensor that controls it?
Thanks for your help.
Rick

Answer
Hi Rick:

there are a few things you can check here. #1 the throttle body and throttle plate may be carboned up bad they can be cleaned with either carb cleaner or are intake cleaner. Secondly if there is any kind of vacuum leak on a fule injected engine the idle speed will be higher then normal. check the vacuum lines going from the engine to the body. they are on the right side of the van just above the serpantine belt. I belive there are 2 of them on that van. Trace them back to the engine and see if any of the rubber lines are cracked or split. Good luck :)