high idle

Hope I can get some help on this one. 1985 CV efi 302 has been sitting off and on for several years with little or no driving done to it. When I first start it, the idle is what I would expect from a cold engine slightly higer than normal idle. I'll drive it to the gas station about 6 miles away and stop and the idle will run away very high. I don't have a tach so I don't know what its turning but it's high. I can shut it off and restart it and it still races, but if I go in the store and come back out and start it, it idles fine. I have spent quite a bit of time under the hood of a 94 Tbird troubleshooting fuel/sensor problems but have never seen a efi system that resembles this turkey. Any help as always is greatly appreciated.