This morning I started up my 06 5.4L and it was running like crap. I stopped to get some gas and bought some Gum Out fuel system cleaner. About 15 minutes later I stopped at a stop sign, when I went to got the truck backfired and stalled. It scared the poop out of me. It's started right up, and after it was running like a champ. I'm thinking it was something with the fuel system. Anyone know what this could be?