Have a 1986 IROC 305 4bl. When I first start up engine idle is basically ok, 6 to 7 rpm. After car is driven for a while and heats up it begins to idle high between 12 to 14 and the check engine lite comes on. You are unable to tap it down. Eventually after 3 or 4 minutes it starts to come back down. According to manual temp guage I installed the car heats up to 240 - 245 during this period. Other than that the car is a good driver. Has anyone experienced this problem before? Solution? From Monmouth County, NJ, Jersey Shore. Anyone know a place I can take it to? Thanks