Any codes on mb star? I had similar issues, replaced:
2x Mass airflow,
water pump, boost pressure sensor, intake manifold, refurbished injectors, fuel filter housing, all of the solenoids and vacuum system sensors along with vacuum pump, oil cooler gaskets, oil filler cap gasket(awaiting actual cap now), rocker cover gasket, now awaiting oil separator repair kit...
I had misfiring too but it went away after a while , probably loads of crap in the cylinder got cleaned out...
However I use shell diesel v power .
Attached is picture of oil two weeks after replacement. Used liqui moly engine cleaner and little bit of diesel
Check your diagnostic codes.
2x Mass airflow,
water pump, boost pressure sensor, intake manifold, refurbished injectors, fuel filter housing, all of the solenoids and vacuum system sensors along with vacuum pump, oil cooler gaskets, oil filler cap gasket(awaiting actual cap now), rocker cover gasket, now awaiting oil separator repair kit...
I had misfiring too but it went away after a while , probably loads of crap in the cylinder got cleaned out...
However I use shell diesel v power .
Attached is picture of oil two weeks after replacement. Used liqui moly engine cleaner and little bit of diesel

Check your diagnostic codes.