When changing all 7 coils
I mean 6 coils, 2 were defective! They were replaced under warranty from BMW. I had similar issues as you and when I put my old coils back in 3 and 4, problem was solved. I am not sure if this answers your question or fixes your problem, but I thought I chime in. The parts person at BMW told me that the new coils are known for defects from the factory!