Hi i have a question on what can be causing my car to do this..1987 iroc with 305 tpi...when the car warms up and is in drive the car will like go up in idle and come down when i let off the gas it not like alot but its noticeable..it will go maybe from the 5 to the 10 in rpms and shoot up real quick and just come down what can be causing this..im sorry if its not the best explanation but its hard to explain it..its like if ur stepping on the gas and letting go real quick...any help would be great thanks.

 

The number one cause of a surging idle is a fault in the EGR system. May want to tear down the intake and inspect/clean the EGR valve itself as well as check out the rest of the system.

 

well ima be doing that soon then cause my intake manifold gaskets need to be replaced ill be sure to check that out. thanks.