L78 idling issues

[azcamaros]

Two things come to mind. Have you adjusted the valves recently? If you have you may want to recheck them. I recently helped a friend with the same symtoms and discovered he had recently set his valves and got them a little too tight. As soon as our summer heat set in the car started giving him similar problems to yours. His coolant temp said 190 but the ambient temp. did make a differance.. Another thought is the rear power-valve. I have chased idle issues for days and overlooked the rear powervalve on my LT-1 vette. I don't no why it went bad but after a day of troubleshooting fun I replaced the re powervalve and I was back in action. I run my cars in 110 degree heat and my idle issues have never been related to boiling fuel, just other weird stuff.. Good luck