well here is a little hint, a engine that is running lean will have more power then one running too rich.
sounds to me your car is going into what we call R&R mode. rich & retard. but first you need to do this test before we can move on any further. keep your eye on the boost gauge or get someone else to drive while you look at it. does it go over 12psi at all ? does it go up to 15 ? hold it and only back of if it goes over 15 16psi (the turbo won't shit itself if you do this, its only if you constantly run it at higher boost pressures)