I have a 89 f250 with a 460 and a c6 transmission. The truck sat for about 10 years until I got it this past summer. Replaced fuel tank both fuel pumps switching valve fuel filter FPR and injectors. Truck starts up and cuts off unless you feather throttle. So I replaced all relays and all sensors on the motor, O2 sensor and PCM and MAP sensor. Same problem. I have since put a new motor and transmission in the truck and cannot for the life of me figure this thing out. The truck will run if you unplug the vacuum from the map sensor, but not like it is supposed to do. The truck starts up fine will run for a few seconds and cut off. It will always start right back up but cut right back off unless the vacuum from the map sensor is unplugged. I have checked the fuel pressure its 35 key on engine off no about 30psi running. Please please help. Very frustrating. Any advice would be very much appreciated. Thanks. Matt

 

Is your truck throwing a code? I'd start there.