I have a tech question that local shops have been unable to answer. Would like to get possible answers to the problem . The problem is a high idle when first started, sometimes as high as 2000rpm. It takes about 10 seconds to slow down enough to pull it in gear. The car is a 95 Riviera with supercharger. Idle afterengine slow down is 850.Edited by: trader ART

there are 3 main sensors that affect idle. the most integral sensor for timing fuel and spark is the tps. the iac, and the mass air flow could also change ur idle as well.

but there are many reasons for a situation like this. the best thing to do is run a scan tool on it and try to get a trouble code. and go from there