ok guys I got another problem with the ranger check engine light is back on code says both banks running rich in live data on the scanner you can see the o2 sensors fluctuating between around .030 to around .850 which is normal the problem is the longer it runs the sensors start reading higher without fluctuated last reading I got was around .935 to .940 on both sides and finally turned the check engine light again I have replaced regulator plugs wires checked for vaccum leaks the maf sensor reads 1 at idle and jumps as soon as I hit the gas so pretty sure its good im down to either replacing o2 sensors or computer have any of you guys had problem with this any help would be greatly appreciated

 

WAG alert. Running rich might mean it's running as though it was cold. What t-stat do you have, and check the temp sensor as well.

Serving suggestion.

Vacuum leak would give you lean, these engines will do that too.

Maybe dirty injectors?

 

I did replace the temp sensor and t-stat that was my first thought too . With the scanner in live data I sprayed around everything with carb cleaner and there were no spikes on the o2 sensors so I don't think I have vaccum leaks gonna have the converter checked out next I replaced the upstream o2 sensors buy the regulator was bad so they may have been damaged

 

Hold on, don't toss any more parts at this problem unless they test bad.

Since you say you can monitor live PID data, have your ELM scan tool running FORScan, if that's what you have, look for trouble code clues & post All code Numbers it finds, as they can help focus a trouble shoot.

What does the scan tool say both cylinder banks fuel trim looks like?

Use your fuel pressure gauge to monitor operating fuel pressure & engine off fuel pressure bleed down rate, to see if you may have a injector with a runny nose.

Post up what the scan tool says the MAF sensor PID is reading at idle & at say 2000-2500 rpm.
Since the IAT is part of the MAF sensor assy, have it's PID monitored, to see if it's believable.

I'm not clear on some things. You posted above that you've replaced the "regulator", did you mean the fuel pressure regulator? If so, Rockledge reminded us in your 2016 blowing black smoke thread here https://www.ford-trucks.com/forums/1...ack-smoke.html, that in 98 Ford moved the fpr to the in tank fuel pump assy & the under hood fuel rail can that looks like the old fpr, is a fuel pressure pulse damper, not a pressure regulator. SO, in your May 2017 thread here https://www.ford-trucks.com/forums/1...regulator.html, what did you replace, the pulse damper, or fuel pump/regulator assy?

If you replaced the fuel pump again, you need to find out why their going bad so quickly, as that's not normal?

You also say you've replaced the "temp sensor", so what temp sensor has been replaced & why was it replaced, did you have a trouble code for it, or was it testing bad? Was it the single wire temp gauge sensor, or the two wire ECT sensor?

If you've been driving this puppy while it's dumping fuel into the engine such that it's blowing black smoke, the cat converter has likely been seriously over heated, so exhaust back pressure should be checked if the engine is down on power at throttle up, or has been running hot.
You can do a back pressure test with a vacuum gauge, by scrolling down & following scenario #14 here How to Use and Interpret a Vacuum Gauge

Let us know what you find.