With the misfire codes I would look into replacing spark plugs if those are originals, the lean running and misfire could ALSO be a ripped intake elbow boot, i'm sure you must have heard of the known problem with the M54, its an E46 problem too.

The intake boot is 15 bucks from dealer and OEM NGK plugs are 40 dollars, after you fix your O2 sensor issue I'd look into those two.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards