Buddy of mine has a 99' F-250. Says truck sputters often, and dies on occasion, always at low rpm's. He's changed the primary fuel filter and no change. He's about to change the fuel pump, but isn't sure of its location, hasn't looked for it yet, so any info on it would be appreciated. Also, read somewhere that a cam sensor sometimes causes this problem?? Not sure about that at all. His last thought is somebody put regular gas in it... Any help or info is appreciated.