same issue, limp mode upon hard acceleration (happened to me twice within three weeks of owning my car).
I'm glad I found this DIY, helped me. I was able to just remove the two front engine cover hex screws and lift the engine cover slightly and bent it to the left (the engine cover was flexible enough and i didn't have to remove the charcoal filter doing it this way, but I do not recommend doing it that way as you can permanently bend it or snap the engine cover if not careful). I did not remove the snorkel as my hands fit fine in the gap (I have the oil cooler as well). Removed the intake, then exhaust. I had limp modes for the exhaust so I cleaned that one out with brake cleaner and let it dry for a minute swinging it back-n-forth in the air. Re-installed it in reverse order making sure I swap the intake/exhaust solenoids. It only took me 10minutes to do this and it was my first time.
Instantly I noticed my part-throttle acceleration is stronger and more responsive, no difference @ WOT though, and the stumble/misfire @ idle is reduced. It's only been 4 days since I've done this, but no reports of limp modes or ghost codes yet.
E90 LCI M3 7-DCT Interlagos Blue/Novillo Silver
[MS Pullies|K&N drop-in|Primary Cat Delete| Evolve Stage II]