Engine running rich

What codes are you getting?

It sounds like there is a problem with the MAF sensors cleaning doesn't work most of the time or the temp sensor. Have you had them checked? Also, when I say "Temp Sensor" I am referring to the ambient air temp sensor not the sending unit.

How do you know the engine is running rich? Fuel smell? Poor mileage? Black smoke?
When was the last time it had a tune up? It sounds like you have a MAF sensor that needs to be replaced. When these sensors go bad they sometimes do not trigger a code.

How do you know it is running rich? If there are no codes saying it is rich then what makes you think it is? Were the plugs carbon covered? Was the fuel pressure tested as high? What is showing that it is running rich? Have the injectors been tested for flow rate? Without knowing what you are seeing as the symptoms of it running rich there is no way to answer the question. You could throw a lot of parts at it and never repair it.

2003 Ford Ranger 3.0L engine, automatic.

I have this truck running full rich (11% CO) with 2 trouble codes. PO2196 and PO2298 for both banks oxygen sensor running full rich. I checked mass air flow sensor and looks ok at about 5.4 pounds per minute. Replaced fuel pressure regulator and no change. Checked fuel pressure and found at 66 psi/idle withing specs. Checked compression. Good compression. Checked ECT sensor and working normal. Checked circuits for all 3 O2 Sensors and checked out fine. Disconnected mass air flow sensor to see if it changes and no changes observed. Disconnected ECT sensor with same results. Live data shows fuel trim at -21 on both banks indicating it is trying to lean out mixture. Also this is what is whats throwing me off. Truck starts fine everytime?Replaced the ECM after above fault tracing and no change. Did I overlook a step? Any help would be apreciated.

Hi
Well you have covered about everything other stuff that can cause faults leaking injectors, see if pressure hold after engine off also high fuel pressure what is pressure off idle? PCV inop and EGR gasket leak and unseated and sealed oil stick and intake restriction and oil overfilled.
Hope this helps
Thanks for donate

I never did let you know what the final results were here for the archives? I threw in the white flag on this one and had customer take it in to the dealership. It turned out customer had replaced the engine but had a different intake on here. So it had an internal vaccum leak. The dealership installed the correct intake and problem was fixed. Thanks for all your help.

Check the engine coolant temp sensor, Fuel pressure, with particular attention to the pressure regulator...or cloggeg return line.
https://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.

Hi zp3design, Welcome to 2carpros and TY for the donation

Could be an intermittent problem with one of the following causing it to run rich.

1. Excessive fuel pressure can be cause by restricted fuel return line or defective fuel pressure regulator.
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.

Check the following:

1. Excessive fuel pressure can be cause by restricted fuel return line

2. Defective Oxygen Sensors.

3. Leaking injectors and fuel pressure regulator.

4. Coolant temperature sensor out of calibration.

5. Restricted air intake system.