I have a 94 Ranger 4.0 liter.
it started idleing and running rough. horrible fuel mileage.
I've changed, MAF, TPS, IAC, Fuel pressure regulator, plugs and wires, and cut a hole in the cat thinking it may be plugged.
It starts fine and idles ok for about 5 minutes, then it idles rough enough to rev it up, let off the fuel, and it dies..

 

Welcome to the forum

Shouldn't be changing that many things, sensors rarely have problems although many do change them, estimate is that 90% of sensors or controls on an engine were working fine when changed.

The spark plugs and wires are good to change, the 4.0l OHV engines eat spark plugs, use regular copper or nickle plugs or Double Platinum, never use single platinum in any Ranger engine, waste of money.

1994 4.0l OHV uses an EDIS-6 module for spark, outside of a front end collision breaking this module(it's on rad support, front side) they never fail

No gas pedal on fuel injected engines, just "air" pedal, it lets in more air doesn't add gas like carb engine pedal did, just FYI.
So when you let off on the "gas pedal" you are cutting off AIR flow not fuel

The 5 minutes good cold running is a good catch.
The fuel injection computer runs in Open Loop until engine warms up
Open Loop means the computer is using air/fuel mix tables put in its memory at the factory, so air/fuel mix is based strictly on RPM, and throttle position, so not really using many sensors, TPS and Crank sensors

When engine is warmed up the computer changes to Closed Loop
In Closed Loop the computer is using the MAF sensor and O2 sensors to calculate best air/fuel mix
And this is when your engine has the problem.

Nice thing about computer controlled engines is that they can often point you in the right direction when there is a problem, especially Closed Loop problems.

When you turn on the key the CEL(check engine light) should come on, does it?

It will then go off after start up

If your CEL is not coming on then could just be a burnt out bulb or computer is your problem.

But in any case you will need to check codes, there are a few reasons to do this
One, of course, is to get any codes currently in computers memory
Next is to clear the codes and then set new codes on purpose to make sure computer is working like it should.
If computer is the problem you could build a whole new truck around it and it would still run like crap.

Read here: Ford Ranger - Testing EEC-IV Equipped Engines

On the 1994 it will use 3 digit codes
And if CEL is working codes will flash it when self test jumper is installed

The connector for this is in engine bay between power brake booster and fender, attached to wiring harness for computer, computer is just below this location between fender and firewall

Install the jumper wire and turn on the key, wait a few seconds and you should start to see the CEL flashing

1 pause 1 pause 1 long pause..........next code
There are no 0's just 1 to 9, and ALL will be 3 digits

Code list here: OBD-I Diagnostic Trouble Code (DTC) Applications - Ford 3-Digit Codes

After seeing if there are any codes, unhook battery, both cables, and touch the cables together, this will drain all power from the computer, clearing it's memory

So all codes are cleared, hook up battery
Start cold engine
Unplug MAF sensor while it is running

On upper intake drivers side, about 1/2 way is the IAT(intake air temp) sensor, unplug it as well.

CEL should come on, may take a minute or two but if should come on when MAF and IAT codes are set

Then read the Codes again to make sure computer is working as it should

 

Be sure to check all the vacumn lines coming off the throttle body. They get old and brittle and can cause idling problems.