Yeah the AFR during WOT is fine as it hovers around 12.5. A couple things really jump out and those are:
- Mass air flow HFM readings seem to be really erratic.
- You have a pretty pronounced dip in relative Air filling around the same area that the Mass air flow goes crazy.
Not sure what is causing that but whatever it is likely causes the boost to fall below target as well.
I wonder if your issue is a dirty/faulty MAF. Does the car have aftermarket filters as I know the oil types can cause issues with the MAFs.
This log is from my car although it's the stage 1 93 OTS it should give you a reference point to help look for odd patterns in your own.
https://www.bootmod3.net/log?id=5f4d...0b430e1cba5860