Not sure if the Rangers with 2.5l got PATS system in '99, other Rangers did.
PATS system can cause a no start, anti-theft light would be flashing if this was the case.
Spark and fuel injection all starts with the Crank Position sensor(CKP).
This is on the Crank shaft.
It sends a pulse to the computer for #1 TDC and then rotational degrees.
Computer doesn't even know you are cranking the engine if CKP isn't sending a pulse.
When computer gets CKP pulse it starts the spark and then starts the fuel injectors using the same pulse.
Cam position sensor(CPS) is used to fine tune spark advance and injector timing but engine can run OK with out this sensor.
But no CKP pulse means no start.
There are codes if CKP is starting to fail, have you tried reading the codes in memory.