when the motor comes up on 5g it sounds like its rev limiter it will just bounce off it... it doesnt stall... not quite sure how to check detonation but the spark plugs are all good. now when i let my car sit for a long time the engine turns but wont start i turn my key to on but i dont try to start it the check engine light comes on and sometimes it stays on for 5 sec and some times 5 min and as soon as it turns off the car starts fine... my friend says something about a fuel pump relay idk... any help appreciated thanks