Just FYI, all Rangers came with factory CAI.
Extra MPG and more power are opposites.
You get more power by burning more fuel per minute, a 4.0l has more power than a 3.0l because a 4.0l can burn more fuel per minute than a 3.0l.
A turboed engine has more power because it can burn more fuel per minute.
Engines are being made more efficient, so can convert fuel into power better.
And you can also change the power to weight of the vehicle, your 3,300lbs Ranger would have more power and better MPG if it was a 2,500lbs Ranger.
Lose the larger tires, they weigh more and have higher rolling resistance than smaller thinner tires.
Switch to an electric rad fan.
No, there should be no overheating on any trips, long or short.
Engine can run just over halfway mark on gauge if you are climbing a long grade, that is normal.
Over heating would be 3/4 on gauge and up.
If you have an automatic it could be running warmer than it should and the trans cooler is in the radiator so could be transferring some heat causing engine to run warmer.
Fan clutch could be failing, not engaging fully when Rad is hot.
Rad is getting clogged up, if coolant isn't changed every 2 years rads will slowly lose cooling tubes to clogs, as this happens there is less cooling available .
Rads are generally 20% larger than needed, once you lose 20% of the cooling tubes rad simply can't cool coolant fast enough when engine is under load.