Can you help us fix this sick CJ8 Scrambler?

This Jeep Scrambler has a 1999 5.7 Vortec Chevy 350 with a Painless wire harness, 4L60 trans and a Dana 300 t-case.
We have replaced the following parts: Mass air flow sensor, Idle air control sensor, Spark plugs, wired cap, rotor, coil, and ignition module. We have 65 PSI of fuel pressure constant. We did check all fuses and engine related grounds, all good.
It is coding for the O2 sensors. I don't see how replacing them will fix this problem. Correct me if I am wrong.
We could use your help! Got any ideas??
#jeep #engineproblems #chevy350 #scrambler #sick #pleasehelp

[@toomanyprojects8473]

Have you done a vacuum test on the engine?

[@zeeksgarage7750]

No, that is something we have not done. Good idea, thanks!