Cherokee Mix And Match Sensor Trouble

I have a 2001 Cherokee plow truck. It has a 1996 engine installed, with hillbilly workarounds on having 2 O2 sensors instead of 4. It always ran well, but 12 -13mpg. Don't care as it didn't like a few of the O2 sensors, said there was something wrong. Unhooked sensor wire, ran well, been running for 2 years that way, no problems. Lately it hunts while driving and runs rich as hell at idle. If you jump on it, it'll run awesome but idling or cruising it is crazy rich. I replaced all the sensors when I got it, tps map iat iac coolant. I replaced them again under warranty chasing the rich condition. Could a bad computer do this? I am running out of options. Obviously a scan notices the unplugged O2 sensors and says yep that's it, but it was fine for 2 years like that. I don't care about the emissions or inspection, it's a plow truck. Just need to get through the season. Any thoughts?

 

could be a stuck injector.

 

Square body Cherokee 4.0L AW4?

Check fuel pressure and plugs.

 

Ok, since I put a 1996 engine in my 2001 Cherokee a few years ago, it never ran right with all 4 o2 sensors plugged in. Ran great with only two plugged in. My son was greasing it a few weeks ago and saw some plugs disconnected. He plugged them back in and caused the problems to begin. I found them all plugged back in, unplugged the offenders, and poof, runs perfect again. I don’t know why it works this way but don’t care, it’s just a plow truck and winter rot box. It runs great again.