2001 4.6l trouble starting
 

about a month ago my truck started having trouble starting, the only way i can get it to start is by turning the key back and forth a few times to prime the engine and it starts right up, but in the past week its getting harder to start. i changed the fuel filter yesterday and it seemed to do the trick at the time but this morning the problem continued. anyone have any idea what i should try next?

You should check fuel pressure after the pump primes. Is it holding pressure? If not, it could be a leaking injector, bad FP regulator, or fuel pump. An unscientific check would be to just use the tip of a pencil to depress the schrader valve on the fuel line (engine cold, and have a rag close by). You should get a healthy squirt out of the valve after turning the key on.

Can you hear the fuel pump run for a second or two to build pressure when you turn the key on? If not, the fuel pump relay or the pump itself may be failing. If it does run, connect a fuel pressure gauge to the fuel rail and see what you get - it should be at least 30 psi. If it's low, the fuel pressure regulator may be going bad.