[Jacooobs`n]

Hi all fellow M3 owners.
I have a 2007 with 64000miles/107000km.
Started getting a CEL some time ago and reading the code says misfire in cylinder #4 and #6. Tried to swap coils and failure went to #1 and #6 once. Next say back to misfire in #4, and now only #4.
Car goes in limp mode when idle but stop/start a warm engine I managed to get above 2500-3000rpm and car is running perfectly fine up towards the limited (I stop at around 6000rpm as I know there is something wrong).

I replaced all 8 plugs and bought brand new OEM coils from BMW and put that into #4. Car goes OK for a day, the back to limp mode next morning. Code is still misfore in #4.
Yesterday I took all injectors in left bank (passenger #1-#4) out and swapped #4 with #1 and well as cleaned the seat as it was full of debris. Cleared the code, car stands idling for 20 minutes with no problem and I took a 20-minute drive to a friends house, stopped it for 45 minutes and when starting again it goes back in limp mode with misfire in #4 as usual.
When having the plenum off, I got my wife to turn the ignition on and press the right pedal, all trottlevalves are cooperating as far as I can see and while doing this manually I see no slack from the TA`s or any deviations between #4 and the others.
I am out of ideas and might send it off to someone that can inspect the electronics..
Any other suggestions for another try back home is highly appreciated. Budget had a rough 2017 with new crank, rod-bearings, clutch and flywheel