2000 F150 trouble starting

My F-150 has a 5.4L V8 and sometimes it just won't start. The problem has been very sparatic. Mind you the truck has never died while it is running, problem only occurs upon trying to start wether the truck is hot or cold. When it doesn't start the engine will crank and crank but doesn't seem to fire. When this happens I checked the fuel pressure and it is only at 15psi. I have cleaned the IAC value and it tested as being functional along with the fuel tank pressure sensor and the camshaft sensor. I have replaced the fuel pump twice within the last two months with the problem remaining. The problem has become much worse in that the truck hasn't started for over a week now. Any help would be appreciated.

Have you checked the fuel pmp relay or the fuel cut off (inertia) switch?

I have switched the fuel pump relay with a different relay of the same type in the power distribution box with no change. With the inertia switch I have only checked to see that it has not popped up. Not sure if you can check it any other way.

Is there spark? I recently had a similar problem with my 98 F150 4.6. I had a couple of shops look at it and they couldn't figure anything out. I decided to try a crankshaft position sensor. Unfortunately, when I replaced it, the truck was in running condition, so I won't know for sure if that fixed the problem.

What I did find was that the connector from the harness to the sensor was broken. The little tab that latches the connector in place was broken off, probably by a rock, and the connector itself was loose. I'm guessing this was probably my issue as a loose connection would explain the intermittent starting problem

Don't know if it will help or not, but that is what I found on mine.