94 Ranger 4.0, only 73,000 miles. Im getting codes that its running rich and it runs pretty rough. Not as powerful as it used to be and its using more fuel than usual. Im not a super mechanic but im decent. So far I changed out the ICM, PCV valve, TPS, Plugs and wires, fuel pump, fuel pressure regulator and i installed a pretty little fuel pressure gage in the cab so I can keep track of it. After a while that CEL comes on. Codes say its running rich on bank 2. Its got 2 brand new bosch O2 sensors. Also has a brand new (motorcraft) MAF and a K&N air filter. When I turn on the AC, it exacerbates the issue. If any motor heads out there could help I would really appreciate it. I took it to a garage and he said theres no way he could tell because its OBD1 and he can't hook his computer up to it. This sadly made me realize, its hard to find true mechanics anymore. My next venture is the fuel injectors. Any help would be very much appreciated.

 

Sorry to hear you are throwing so many parts at it. Next time come and get some information first. Most parts can be tested. At least you'll have a box of known good devices to swap in for future diagnosis.
Is your fuel pressure guage electrical, and only works with key on, or there's a line plumbed from the gauge to the fuel source? If it's the latter, is it plumbed to the fuel manifold for the injectors (it would probably replace the Schrader valve test port) or a fuel line? If it is plumbed to the fuel manifold there is an easy test you can do to see if the manifold is losing fuel pressure much quicker than it should. If that is happening it's likely one or more injector is not closing completely and whenever the manifold is pressurized additional fuel is leaking into the intake manifold near that/those cylinders, causing it/them to run rich. If you ony have 73k miles in 30 years, there's been some old fuel sitting in those injectors and it has left residue in the injectors.
If you can't do this with the gauge you can do it with a pressure tester or just compare the squirt from the Schrader valve just after pressurizing the manifold to an hour or two later. The manifold should hold pressure for at least a week. Turn the key to the on position and let the fuel pump run for the 1-2 seconds it should do. Do this 2-3 times to make sure it's fully pressurized. Record how much pressure you have on the gauge or assess it from releasing pressure from the test port (be careful). If you used the test port, do the key on thing again to get the manifold repressurized. Let it sit and come back and check in 1-2 hours. The pressure should be the same as just after pressurizing it. If you don't feel comfortable with this a mechanic could do it.
If your fuel pressure gauge is electrical you could try just watching the gauge after pressurizing the manifold. If there's bad leaking you may be ab;e to watch the gauge drop in just a few minutes.
If it seems your injectors aren't closing completely there are videos on YouTube of different ways you can test if they leak under pressure and also clean them. They most likely stil function fine, they're just gummed up on the inside.
One last note, I don't own a 90's era Ranger or a 4.0L so others may have better info for you. I suggesst starting a new thread in the 4.0 OHV and 4.0 SOHC forum (just one forum).

 

Thank you, I never thought about seeing if it loses pressure over time! This will help. Yes the vehicle sat for long periods of time. It was an old guy who owned it and only used it once in a while to go to the store basically. I can do the work myself. Ive had experience with cleaning FI's on motorcycles that sit through winter with gas in them amd vice versa with snowmobiles. I have an electronic fp sensor but I do have the analog style I can hook up for this too to test. Thank you.