Pre-'95 Rangers use the EEC-IV computer which are pretty basic so not alot of issues.
4.0l is a very reliable engine, but don't over heat it, it will crack a head if you do.
The heater cores on these years are the by-pass for the cooling system, this means coolant is always flowing thru the core regardless of "heat setting" inside.
This usually keeps the core fairly clean, but if it sat for awhile it could get clogged up.
If you see the temp gauge start going up above 1/2 then down again randomly, then time to replace the core.
Literally, 4 screws and 2 hose clamps, it will take 20mins the first time, if you every do it again, 10mins.
4.0l only came distributorless and pre-'95 used the EDIS system which is a self-contained "spark" system, it does "talk" to the computer for fuel injector timing(computer runs that) but an EDIS system is autonomous, and very reliable.
4.0l eats many brands of spark plugs, Motorcraft seem to be the best choice for a longer life.
Ranger clutch slaves are a pain, they can be very hard to bleed, and the Master sits almost straight up and down, which can allow it to get air trapped inside.
It is best to use a Self-adjusting Pressure plate for the clutch, as there is no external adjustment, but a standard clutch plate will work.