On any type of car, especially an sc– would a leak(or hole) in a valve cover cause the car to idle weird. ie: high at times(usually around 1500 and slowly dropping down to 800)
Yes, it will idle wierd. All new engines are closed and once air is metered, the computer adjusts fuel etc. for it, so when you have a hole in a valve cover or vacuum line, you've got a problem. Good luck