From what you are describing, it sounds like a lean stumble. Could be pump cam, or squirter size. Or if your jets are really too small. What size squirter does it have?
Did you try a WOT blast & read the A/F ratio?
If now you are only running 4-6 psi of boost pressure as compared to 15 psi of boost pressure, is your A/F ratio richer now only @ 6 PSi of boost pressure? Depending on your A/F ratio @ 6 PSi, you could possibly go leaner on your main jets, only if,you are seeing 11.0 or so A/F ratio now @ WOT.
