I got my truck used from a Ford dealer I was working at, the fuel level sensor was junk too, would go from full/the right level to empty randomly... GM updated the crappy sensors, after my model year of cousre, when I bought it the dealership said they'd pay for the new fuel level sensor, not a whole sending unit either, because they're cheap asses, that bitch was still expensive as hell at the time, and so where whole GM fuel sending units... I was gonna say you could buy a standard high volume intank fuel pump, like from Walbro, and just replace that, but since your guage is faulty too, best just go out replace both with a whole new sending unit...