After engine is warmed up and idling, unplug the 2 wire connector on IAC(idle air control) valve, engine RPMs should drop to 500 or engine may even stall, either is good it means no vacuum leaks.
If RPMs stay at or above 700 then you do have a vacuum leak
Low fuel pressure shows up first at high demand, i.e. climbing hills or driving above 60MPH, engine "runs out of gas"
Mid or lower RPM issues shouldn't be fuel related.
Throttle position sensor(TPS) is a moving part, like a volume control or light dimmer.
When foot is off the gas pedal TPS sends computer under 1volt, .69v to .99v is specified.
As you push down on the gas pedal TPS sends more voltage back to computer, like turning up the volume, with foot "to the floor" TPS sends computer above 4.5volts.
IF(big if) you have a "bad" spot in the TPS computer could "think" you have taken your foot of the gas pedal, i.e. instead of computer getting 2.5volts it drops to 1.5volts so computer lowers fuel amount.
Long shot
But keep track of your "foot position" on the gas pedal to see if roughness happens at a certain "foot position".
Early 2000's Ranger 3.0ls did have coil pack issues, there was a TSB about it, they need to be replaced.