I have a 1998 4.3 vortec throttle body and my truck keeps cranking over but wont start i changed the crank position sensor because it was reading that code awhile back but it didnt fix my problem so i got a fuel pressure guage and when id turn the key to the ignition and start cranking,but it stayed at about 5psi until i stopped turning the key and it jumped to 60 and started decreasing so i changed the fuel pump and fuel filter anyone know what could be wrong with it?