Had head gasket repair on my 1988 vette, when the car returned after the repair the car ran horrible , stalling barely start, Extemley bad shaking when idling , before work was done the idled perfect (smooth and strong) showing no codes , please help what can i do? dont want to be ripped off, i know i have to change wires plugs and distributer, as i think they are the original, but like i said it ran beautiful and smoth before the work, please help dont know what to do here! Please Help!