Hey guys new to forum... Looking for some help.

2003 BMW X5 3.0 P2098 keeps coming back after OBD reset. Sometimes in 10 min other times 2 hrs. Also get misfire code P0313 from time to time.

Says P2098 Post Catalyst Fuel Trim System Too Lean Bank 2

Things I did already
Changed 2nd O2 on Cat 2 no change. But had to weld it cause stripped.
Did smoke test no leaks
Intake Boots are good no cracks.
Use premium gas all the time