I recently purchased a used 2005 Suburban 1500 with 75,000 miles and has a 5.3 V8 Vortec engine. The other morning when it was cold, we started the car and it was running rough. The service light came on the car died a few times when it stopped. We checked the error codes and saw Mass Air Flow and Misfire. We replaced the Mass Air Flow, cleaned out the Throttle body, replaced spark plugs and wires, put fuel injector cleaner and dry gas to see if that would work. Still it is running and idling rough. Any suggestions? I've read it could be intake gasket, and about to replace the fuel injectors - but would like feedback.