HI Guys, I have a 2008 hummer h2. After running it a bit it will come up to a light an fall right on its face. Then it wont start unless I put the pedal to the floor then it will idle again. I cleaned the mass air flow sensor and I run high octane fuel in it. I recently had the crank case sensor replaced and the fuel pump. it through a code for the crank sensor so we replaced it under warranty and fuel pump. Any ideas on what it can be. All fluids are up. thank you