Random misfire and stumble

I recently purchased a 2000 XJ 4.0 auto. The problem I am having is a random misfire plus a significant stumble at about 1/4 throttle. I've already cleaned the throttle body, IAC changed the spark plugs added seafoam injector cleaner there is some improvement but still not 100%. I noticed while watching my scan tool that the timing at idle was reading 5.5 degrees and when the misfire would happen it would become very erratic. Also last night I crawled under the Jeep to do a wiggle test on the wiring at the CPS while it was running to see if it would change anything? while doing this I moved the plug for the front O2 sensor and the idle smoothed out, let go of it and back to running rough. So I unplugged the O2 sensor and the idle has stayed steady and ran much better. I drove it to work that way this morning and only had one or two time that there was a misfire. I checked for codes and the only ones I am getting are a front O2 sensor code because its unplugged and a P0171 lean bank 1. Any help would be appreciated.

The problem seems to be O2 sensor related, yes ? Test the O2 sensors ( or watch the live data ), and inspect/test the O2 sensor wire harness.

Read this and then grab a toothpick -> Scan Tools, O-scopes, and Toothpicks

Thank you for the info. The article was very insightful.