In reference to your problem with "under acceleration it sometimes feels like there is no power, other times like there's a full 350hp"...

I was experiencing the EXACT same problem/symptom for months. I took it in to the dealership a few times (since it was still under warranty) before they finally fixed the problem. They had to replace the intercooler pump and the intake air temp assembly. Now it finally rides like it should!

Good luck with getting yours fixed (if you haven't already).