Welcome to TRS
1995 was when Ranger got the newer EEC-V Computer that could monitor Cat converter function with an O2 sensor after the Cat
So 1994 and earlier won't have that O2 sensor
Its great to replace things hoping to fix a problem, but not always the best, or most economical, approach to engine diagnostics
Newer vehicles that use Fuel Injection and a computer have 2 "modes" of operation, cold engine mode and warm engine mode
Ford calls cold engine mode Open Loop, the computer doesn't use most sensors, they need to warm up first
Warm engine mode is Closed Loop, all sensors are being used now
If engine runs better cold then stumbles when warm(or visa versa) then thats a clue in diagnosing a problem
A fuel pump or pressure issue would be there warm or cold, like any mechanical issue, so pay attention to engine temp as a diagnostic tool
$15 volt/ohm meter can test most sensors and controls on newer vehicles
Just as an FYI, 90% of replaced sensors were working fine, simply unplugging the connector and plugging it back in cleaned the contacts, which is why the new sensor made things better, so save some money and check connections
O2 sensor needs to be changed every 150k miles in normal operation, can't test these, but they are not used in Open Loop(cold) only Closed Loop(warmed up), and would usually set a code when they are near end of life, Lean Codes, and it would be a false Lean so engine would run Rich with lower MPG
$20 vacuum gauge is not a bad investment, all gasoline engines are self powered air pumps, and best way to test any pump is by testing its pressure, in this case negative pressure
2.3l Lima engine uses a timing belt, which can stretch, and that would lower compression, and vacuum, which lowers power and with it MPG
Could also be partially clogged exhaust, which can be tested for with vacuum gauge, limits power and lowers MPG
If you were to spend $35 on tools I think you would be richer in the long run since they can be used to diagnose any year engine/vehicle