[Grip Ronin]

So ive been using, logging and tuning on oft since just about when it was released for this car but ive never encountered this problem. I went turbo about 3 months back and put on shivs base map, it seem to run fine and log fine for a while but recently its started to give weird readings while cruising.
On start up the car will only go as high as 14.2 when it should be 14.7, after about 10 min of driving i will notice it creeping richer and richer until its about 12.9 at partial throttle actual af and commanded. around this point the car will little by little stay in closed loop longer and the command will read 15.05 but actual af will be 12s-13s light throttle. During full throttle it sometimes goes to open loop and af actual and command is normally about right. I have no fault codes and no noticed exhaust leaks. I have tried different maps and reflashing it. shiv is leaning towards 02 sensor but id like to know if anyone has some knowledge on this before i drop a couple hundred on a sensor.
this is a pic of it cruising on the highway, fully warmed up.