Finally found a ruptured vakuum tube going into the FPR, after shortening the tube and reconnecting it to the FPR the car runs without misfiring/choking.

But the idle is still uneven and when testdriving just now the car seemed extremely "lazy" compared to normal behaviour. Disconnecting the MAF, the engine becomes normal and is not "lazy" anymore.

Will probably need to get car diagnosed at a mechanics.