My question is I noticed my valve cover was leaking(when sitting in the cab of truck) so bought a new gasket, removed the valve cover and replaced the gasket, appear to have every hooked up the way it was when we started. So started up truck notice it was running with rough idle that was yesterday 2/17/13, then when you hit throttle it would calm down. Today 2/18/13 started truck to head to work, again rough idle and samething throttle up it was fine, started to drive on road, check engine light started to flash and loose power on the highway. It will move foward at little higher rmps but backward. Was told vaccum lines could be bad and or wires crossed. The engine is a 4.3 Vortec, so any insite on the problem I'd appericate it, don't have scan tool at the moment to check codes.