"If I press the accelerator down only a bit and the car builds boost slownly under load, it will misfire already at 0,2 bar. It will misfire all the way over the entire rpm range.

If I press the accelerator over the point for WOT (Wide Open Throttle), the misfiring seems to be rare, but when it comes it always comes at high rpms and it is harsher. It always comes at higher boosts (0,5-0,6 bar).

The car seem to misfire more when boosting at load with the accelerator pressed slightly than with the accelerator pressed fully."

 ?!? ?!?