I've been experiencing some engine idle issues with my ring for some time now, and I still haven't been able to figure out what the root cause is. Here's the deal: When I first start it up, it idles just fine (I have it set at about 800 rpm, even though it's supposed to be lower). It runs great all day long on surface streets. When I take it on the express way and drive 60mph for about 20 minutes (I don't let the tack get above 3000 rpm), I have a strange idle situation. When I get off the express way and sit at the end of the ramp, it idles at about 1200 and runs really rough (the temp gage reads about 1/2 deflecction). It takes a while of driving on surface streets to get it back running normal again. '79 2F in a FJ40. All emissions controls removed several years ago. Cat converter has been removed. Original carb was replaced with a Rochester 2 barrel. The wiring for the IGN system is all new (and separately fused). The carb has been adjusted recently (it was a little rich, but didn't seem to fix the problem). The valves have been adjusted recently (also didn't seem to fix it). I run 89 octane gas. The fuel pump is an electric rotory type (with a regulator set to 4.5 psi). The choke control on the carb has been removed. The temperature gage wiring is new. Compression check showed all near the lower limit. Would a vacuum leak cause this condition? Would an exhaust leak cause this condition? Any ideas are appreciated.