Hesitation after gear change on WOT

Hello,

I've been having a strange issue on my S3 8L for quite some time now. After I change gears, say from 2nd to 3rd on WOT at about 5k rpm, when I accelerate again the car will boost fine (14 psi stock) but it sputters and hesitate to accelerate at all, even on part throttle or full throttle. I believe it might be fuel related, however I'm not completely sure. Car starts fine however. It makes no difference with full, medium or empty tank. What has already been checked

- VCDS shows no codes
- New Fuel Pump (Deatsch Werks uprated one, it was replaced because the car was struggling to start about a year ago)
- New Fuel Filter (yes, it is fitted the right way)
- Cleaned injectors with ultrasound
- New MAF

I am still to replace the silicon hose that comes from the turbo to the charge pipe because it's in poor condition and sometimes it comes a little bit off causing a slight boost leak, but I don't think this would be the problem. What I feel is that fuel might be returning from the fuel rail and then the car has no fuel pressure left to cope with acceleration again, specially under boost. Might be FPR?

Any thoughts would be appreciated.

Okay so I disconnected the MAF and the car seems to run better. It pulls less, but does not hesitate after lifting the throttle and applying it again. It does hesitate at higher RPMs which I think is normal with the MAF disconnected, as it does not happen with the MAF connected. Thing is, it is a brand new MAF I bought from Amazon, genuine Bosch with the exact same part number. I believe the original Audi is the same as the Bosch, or am I wrong? Maybe the MAF just came faulty.