i have a 2005 chevy colorado 3.5L 5I and i had the problem where my #3 cylinder valve went bad. so i got the head redone, new valve and everything. i also replaced the cam exhaust sensor, the actuator seloniod, got new plugs and coils, and cleaned the throttle body but it still has a rough idle at around 500-700 rpm. also i was test driving it and had reduced power appear on my dash but battery and alternator are good. any thoughts would be appreciated. thanks