usually when you get two conflicting codes that don't make sense you start looking for root causes like a crappy ground somewhere, especially on a 4.0 jeep that usually has a really odd ground configuration. it's probably not going into closed loop anymore with those codes set which could explain why you have awful fuel economy. if it is going into closed loop, it would be good to see what your trims are doing while driving.

i have a 2000 jeep with a 4.0 and i've been forced to learn a lot about it but it's not a lot of fun to work on the computer side of things, that's for sure

what are you using as a scanner/datalogger?