I was thinking your regulater might be increasing your fuel pressure too much therefore giving you too much fuel, overcoming the needle & seat.
Might try a little less base line fuel pressure also, just to see if it changes your A/F mixture.
BTW, how much total timeing are you getting?
Hooking up a fuel pressure gauge just to see your pressure under boost pressure is a good thing.
Goodluck on your next logged runs.
MBHD
