2011 gmc acadia slt car will start. sometimes hesitant sometimes fires right up. run for a couple seconds or a couple min then just shuts off as if you turned the key off but maintains power to the dash, radio, lights. i have checked mass air flow sensor, fuel rail pressure, cleaned throttle body and tested wiring to it, ripped apart fuse panel and wiring harness no damage to ethier. although one bolt holding in wiring harness to fuse box will not full tighten. checked crank. throws no codes. dosent loose spark or compression. looking for the pin out diagram for the ecu to check for loss of power to ecu from ignition, battery, etc. history was it was driving got into traffic and just shut off fires right back up but wont stay running.