bucking jumping at 1200 to 1500 rpm's

Ok let me start by telling the SEARCH police that I have searched and seached this site and many others , looking for new input or ideas so if you are going to tell me to search STOP HERE ! This problem is on a 99 tj not mine helping try to figure this out , couple of weeks age it started bucking @ around 1200 rpm's had it plugged into with a snap-on computer at first it said the cps (wasn't) then upstream o2 (wasn't) map (wasn't) get the picture . This is where we are at right now cps replaced tps replaced seemed to help now right back where we started upstream o2 replaced cleaned the Iac new cap wires coil cam sensor in the cap . Has anyone ever had the computer itself go out , the handheld seems too be creating a map right to the computer . Also checked the downstream o2 seemed to be just fine really starting to run out of ideas he is going to pull what hair he has left out any ideas would be appreciated , Thanks (99 tj 4.0 5 spd little over 100,000 on the ticker)

fuel delivery? Did you happen to check fuel pressure?

also check for vac leak

Haven't check pressure yet with gauge but seat of the pants tell me it is fine , this is just at the 1200 to 1500 range you let off the gas goes away nail the gas it never misses a beat ,I will check the pressure though .