I do however feel we should eliminate all other possibilities before replacing an expensive item such as the regulator, although it does sound as though you may be in need of that regardless. Have you checked the fuel injector to be sure it is not stuck open and leaking through? without the truck running there should be no fuel flow through the injector. The injector is located on the lower rear portion of the throttle body and has two wires going to it. It is held in by two ten mm bolts. Remove it and make sure there is no fuel flow when not cranking. (spray a little gum cutter into a cap and hold the end of the injector in the liquid to check for fuel flow) Then crank the engine and insure there is pulses of fuel flow while cranking.