I have a 1999 Ford Explorer XLT that will not start. I replaced the fuel pump and filter, checked the relays and fuses. No fuel pressure coming from the shrader valve. Truck will start when I spray starting fluid in the intake. It starts and runs but then cuts off when its gone. Could it possibly be the cam shaft position sensor, crank shaft position sensor, or the oil pressure switch? I checked the inertia switch also and its not tricked.