It could be solenoid, starter, battery, alternator not CHARGING the battery or corroded battery terminals.
Low battery voltage .?
The starter or battery cables/terminals are corrode.
the clutch on your A/C compressor needs to be replaced.
Anti-rattle clips not installed properly
Cables clean and tight on the battery? If so probably the starter solenoid. (Older F150s located just behind the battery on the passenger inner fender).
The head gasket is about to blow.....Typical ford..
your barrins in the wheels
There are a couple of a reasons why a 1994 Ford F150 truck will not start. The truck may have a dead battery or the spark plugs need to be replaced.
Check your battery connections for corrosion or being loose. battery might be dead maybe you left a light on or something
The computer
Ford Dealer can help you. And tell you if there is anything wrong with your 2003 F150.
There could be loose rings in the engine that would cause this. The valves on the engine may also be chattering.