Allright...little update...

its the first cylinder which doesnt work at idle...
ive changed the leads with each other....no result..
ive changed the plugs woth each other...also no result..
ive newed the the plastic things on the distributor...where the leads hanging on..dont know the word...also no result...

mmm...

could this be an injector problem...i find it strange because it only wont work at idle...

there is no messy stuff in the coolant..and also not on the oilstick...
the car runs normal when driving...but positive boost at 0.5bar and more it misfires..i guess at the first cyl...