stuck lifter, m117, engine runs worse after warmup: Oxygen Sensor?

[d333gs]

Hi
Have a stuck lifter in a 86 560 SL. The car had been sitting for a while before the lifter problem so , befor opening the head up I did an oil/filter change and added some lifter additive and I have been driving it to see if the lifter will un stick.
The engine runs allmost perfectly for the first 15 min, (except for the lifter noise and tremble) and then acts doggy, feels likes it's missing (no back fire) .

Question:is the OXY sensor kicking in after warmup and adding to the problem?

Thanks a lot guys,
Great reading here