Just bought a 2000 Silverado... very clean truck, low milage.... all is well except that the fuel guage does not seem to work consistently. When I start the truck, the guage shows empty, the "Low Fuel" indicator lights up in the dash and as I'm driving down the road, the guage starts working on and off... Anyone have this problem? Is it the sending unit in the tank? or an electrical issue under the dash? Any thoughts would be appreciated!!!