Phil, Do have acess to GM Service information? It might be this=#04-06-04-001C: LB7/LBZ/LLY/LMM - Intermittent Driveability Conditions-No Crank, Crank No Start, Hard to Start, MIL/SES, Hesitation, Lack of Power, Surge, Misfire, Fuel Knock, IPC Indicates No Oil... Login to read more.