do you have access to a "INPA" enpowered laptop?
if yes, then you could try the "Unruhemessung" Not sure how it´s called in english - It´s the Measurement you can start to see which cylinder is running not a smooth as the others. The Coil´s *can* bei DOA, are they aftermarket or OEM Bmw?
Switching of the After cat sensors is usually not needed - but the BEFORE cat sensors are quite important.
While you are already busy spending money - switch the "LMM" Air Mass measurement things in front of the throttlevalve - which you can also switch out while you are at it
Then change the Valve cover gaskets, and your engine will pur as new
