Was out tonight and car fell on its face misfire... code ,random misfire and then a cylinder 5 misfire pulled the plug on 5 looks fine switched coil packs still missing. You drive the car and the engine light flashes and then goes away. I read about the VCT solenoid going bad the car has 16000 miles on it, it has Amsoil 0-30 in it. How do you tell witch one is bad?