2002 F150, 4.2L V6 Sport. Had a problem getting it started one day. Engine cranked but wouldn't start. After a few minutes and pumping the gas pedal it started and then started 3 or 4 more times over the next couple of days. Now it cranks but won't start at all. I removed the air filter connection and sprayed starter fluid in and it starts but dies as soon as you stop with the starter fluid. Have changed the fuel filter with no change. Dropped the fuel tank and replaced the fuel pump with no change. I can hear the old and new fuel pump operate when the key is turned on to prime the line. Then a few seconds later I hear a whooosh sound. I believe the whooosh is the fuel return line returning fuel to the gas tank. Truck has 130K miles on it. Does anyone have ideas about what it could be? My guess is either the fuel pressure regulator has gone bad or the idle air control has gone bad. The IAC appears to be no problem to change or clean but haven't located the fuel pressure regulator yet. My understanding is it is hard to get at. Any help would be greatly appreciated.