How can you tell if a valve cover gasket is bad? I just bought my truck and it feels sluggish and underpowered and idles like 1 cylinder is firing good.And when the truck is cold and i try to drive it it will bearly move (i mean bearly)until it gets some temp in the engine. I had the truck running and pulled the plugs on the passenger side and the idle changed a little, but when i pulled the one on the drivers side the idle got alot worse. I just want to know for sure before i do all the work pulling the valve cover off. I am taking it to someone tomorrow to run a diagnostic to see.... Thanks for the help guys.