while routine driving on freeway @70mph, a loud BANG! (probably metallic), a modest slowing lurch, no power...shift to neutral... towed home. tranny works, can move truck with the starter, will not push start. Starter, accelerator linkage, electrical systems, all work; 2 month old IP (new) and fuel filter (which have run perfectly). Maybe the lift pump, but why the powerful Bang and lurch?? your ideas appreciated