it sounds like your idle control is sticking it can be remove by a techician and cleaned with carb cleaner the mechanism sometimes can get oiled up and stick ,but if its the electrical side of the idle control valve then it would have to be replaced . there is one other possible cause of the hunting if there is a air leak from a vaccumn hose listen when the engine is ticking over to see if you can hear a hissing noise
thorby
June 2011