Sometimes when O2 sensors go out (I.E. stuck center/lean/rich) they give erroneous readings before they tend towards the wrong reading. I guess the next question is... Does the jeep do this cold, or warm, or both. If it is sputtering only warm (Closed loop) then it may just be a bad O2 sensor. If it does it cold/both, then it is a basic sensor used in both open and closed loop (MAP,CPS).

91 YJ
2 Seater Sand Rail
Handfull of other fun toys...
And a brand new, spit shined, B.S.
Oh, and a job to boot.