94 tempo running rich bad idle. I have done tps mass air flow senor plugs wire cap rotor fuel fitler coolant temp senor o2 senor a ir value clean throttle body

lots of causes , injector leaks sure. is one of many.
this is EFI and EFI only controls injection.(and spark)

it and all its inputs. do. called sensors.
1998 car in usa the scan tool tells you what all sensors are doing,called PID scans and DTC errors of any kind
25 year old car. and engine and all parts on it.

ALL fuses good?
NEXT:
scan the PCM see P03xx error or others? (scan it)
p0171 And P0174? P03xx codes and more do the scans.
engine good first. for sure this OLD.
we do engine tests.
compression over 150psi on all 8 cylinders.????
vacuum gauge at 20" HG at idle and not BOUNCING
we use tools to find cause. gue$$ing can be endless and super expensive or worse adding on wrong parts.
SPARK:
8 spark plugs all new, and all 8 COP boots new
boots never every lasted, 25years, nor spark plugs
and last fueling , cant burn fuel correctly with bad engine or bad spark CAN not.

SENSORs and stuff:
MAF SENSOR BAD OR WEAK, OR NEVER CLEAN IN 25 YEARS WILL RUN LEAN .
FPR 25 YEARS OLD ARE BAD. THEY ALLOW FUEL PRESSURE TO BE CRAZY TOO HIGH OR LOW
CALLED OUT OF SPEC. (or gets stuck at max PSI)
THE VACUUM HOSE TO FPR MISSING FUEL PRESSURE WILL BE WAY WAY TOO HIGH and super RICH BURN.!
IF FPR VAC NIPPILLE IS LEAKING FUEL IT IS BAD.
Fuel Pressure Engine Running kPa (psi) (28-45)
Key On Engine Off kPa (psi) 35-45)
THIS SPECS ARE DECEIVING,
EFI LAWS, KEY ON PRESSURE IS ALWAYS HIGHEST PSI. (DUE TO ZERO VACUUM)
AND RUNNING ENG AND VACUUM MAX INCHES HG, IS LOWEST PSI FUEL;. IF NOT RUNS RICH AS A PIG.
KEY ON PRESSURE FPR IS 5 TO 6 PSI FUEL LOWER THAN AT IDLE. <THAT IS ITS A#1 TOP JOB THIS.

EXAMPLE 40 PSI KEYON PRESSURE.
THE IDLE WILL BE ABOUT 35.(20 "HG IDLE)
THE FPR DOES ALL THAT.
IF NOT ALL INJECTOR , OVER OR UNDER INJECT.
PERSONALLY I NEVER EVER TRUST ANY OLD FPR. I HAVE HAND VACUUM PUMP TO TEST IT FULLY. AND HAVE FOR 4DECADES.MID 1980S

INJECTOR LEAK DOWN TESTS FAIL OR INJECTOR BALANCE TEST FAILS ,TOLD IN SM= SERVICE MANUAL.
BASICS BAD: IS THIS:
THERMOSTAT BAD. OR MISSING, OR NOT AT 180F TO 200F TEMP STUCK AT 150F BAD BAD BAD.

ECT BAD, SHOWS 150F WHEN COOLANT IS 180F
CAUSING:SUPER RICH INJECTIONS.
SO PCM IS STUCK IN COLD STARTUP MODE FOR EVER AND BURNS FUEL LIKE MAD.

SURE O2 SENSORS DEAD OR EXH CRACKS NEAR BY THEM MAKES THEM LIE AND EFI GOES HOG WILD RICK. SURE.

WHY NOT SCAN THE PCM FIRST.
AND SEE WHAT IS WRONG FIRST.
SAVE TONS OF GUESSING

LAST AND NOT THE LEAST
YOU CAN SCAN ANY PCM AND SEE IF IT IS IN LIMPHOME MODE AND IF IS, IT BURNS FUEL LIKE CRAZY
AND SEE TOO ,CLOSE LOOP MODE IS DEAD
FULLY HOT ENGINE.
YOU CAN SEE LTFT EFI IS STUCK FULL RICH.
AND DTC ERRORS ,LOTS?
THIS IS NOT GUESS IT IS TESTING USES REAL TOOLS. TO FIND CAUSE.

most bad cat converters do not affect idle as there is little gas flow problem at that speed
different at speed or full throttle
try using a scan tool to reset the ECM after all of the new parts
the sensors (O2 ) are not the faulty units as listed by the code p 2198 which are the heated oxygen sensors in the exhaust manifolds before the cat converters -- fault stuck rich
AS these senors (HO2S) report the gas composition to the ECM to adjust air /fuel ratio it is very possible that these being faulty , the ecm is allowing extra fuel into the engine and in effect running on choke
Using the throttle to idle suggests that the problem is air /fuel mixture for and idling engine and I would be investigating that area as the problem

WHEN THE FUEL TEST WAS DONE DID THEY CHECK VOLUME AS WELL AS PRESSURE? YOU CAN HAVE GOOD PRESSURE BUT NOT ENOUGH VOLUME

Check fuel pressure and fuel delivery. MAP sensor also needs to be checked.

Is there an engine light on? What condition are the spark plugs in? After 8 minutes, the engine is most likely up to operating temperature, therefor would be in closed loop, getting info from the o2 sensors and air temp, coolant temp sensors. One of these sensors could be causing an issue. Also, have you tried to spray out the throttle body with an intake cleaner to remove build up? How many miles are on your Ranger?

First, your engine has fuel injection and has no choke. In a carbureted car, the reason there is a choke is to restrict air flow in order to change the mixture of air and fuel entering the engine. Since fuel flow cannot be easily altered you just limit the amount of air going in, resulting in a rich mixture.
In an injected engine, air flow remains the same and additional fuel is added by keeping the injectors open longer.
The computer gets information from several sensors in order to know when the engine is cold or hot, or, to know what the outside air temp is. The sensors that are primarily responsible for that are the coolant temp sender and the intake manifold air temp sender. However, the coolant temp sender cannot work properly unless you have the correct thermostat installed (195 degree (f)) But, generally that helps more in making it run correctly after it's warm.
Therefore, check or replace the coolant temp sender and the intake manifold air temp sender.
Testing can be done using a digital multi meter following instructions found in either chiltons or haynes manuals,
Also make sure spark plugs, ignition wires and the cap, rotor, and coil (if you have them) are in good condition as when cold, any moisture or condensation on ignition parts can cuase spark bleed off and make the engine run poorly as well.

check for vacuum leaks, check distributor cap and rotor button, clean or replace as necessary. Use quality injector cleaner.

You have a fuel injected car. Things that can cause too rich would be a bad altitude sensor like the map or mass air flow depending on which one you have.
Anything that would cause excess air to go into the exhaust system like a cracked exhaust pipe before the 02 sensor, or low compression, or a stuck open pcv valve, intake gaskets, throttle body base gasket.
Or a Throttle position sensor which is telling the computer you foot is on the gas when it is not.
Its possible you have a bad PCM,, or coolant temp sensor saying the motor is still cold as its warming up.
Its possible you have a vacuum hose somewhere on the engine with a big crack in it or its just inplugged and you dont see it.

But my first guess would be possibly a bad computer.
Try creating a big vacuum leak when its loading up. It should run better.

Also if you have an egr valve it could be stuck open a little causing excess air or an idle air control valve stuck open.

Does it clean up if you rev it up or does it blow black smoke reved and at idle. This could point towards the altitude sensor.

was the code for rich or lean? may try cleaning mass air flow sensor. it is in the air intake tube and has a flat wire connector. take out of tube and take four torx bolts out and clean with mass air flow cleaner or brake cleaner and put back in when dry. or it could be a bad wire on the o2 harness. look for chaffing or broken wires in harness by o2. also could be the exhaust system has a slight blockage. could also be some other things but try these first.

• The PCM doesn't even see the O2 sensor until engine temp has reached operating temp,the vehicle goes from open loop when cold,to closed loop when warm,where the PCM uses the O2 sensor to measure the rich/lean of the exhaust content,and from that,adjust fuel richness to achieve 14.7 to 1 air/fuel ratio.So when cold,the O2 sensor is out of the picture anyways.When unplugging sensors,it can be deceitful.The PCM has a program whereas,if a critical sensor (such as the mass air flow) is somehow damaged and out of the picture,the PCM will substitue a generic value that will allow the engine to stay running.So,by unplugging the MAF,it did try to run on it's own better than plugged in,there's the problem area.The vehicle is running better with the MAF unplugged,because the MAF is likely bad,and the PCM is substituting it's generic value when it IS unplugged.Something to recheckThe PROM update is a newer program for the PCM,and likely won't fix it unless the PCM is bad.I would try a good used PCM as a last or later resort,because i have seen my fair share of defective PCM's too.I have taken some PCM's apart,and found capacitors that had gone bad and leaked all over the circuit board,mostly Honda and Mitsubishi and Chrysler though.Good luck,keep me posted.