MBC set to 20psi, open element air filter installed:

1st test drive:

Normal driving - OK.
1/2 to 3/4 throttle - felt like a slight loss of power, car did not seem to pull as well, not smooth.
WOT - fuel cut around 5,500rpm @ wot.

Removed MBC raplaced w/ factory setup, Open element filter:

2nd teast drive:

Normal driving - OK
1/2 to 3/4 throttle - Car pulled much better, however, still doesn't pull smooth throughout the RPM band.
WOT - No fuel cut. Probably due to the boost taper.

Reinstalled factory air box, filter, and MBC set to 20psi.:

3rd test drive:

Normal driving - OK, may have noticed slight decrease in throttle responce, may have been in my head, though.
1/2 to 3/4 throttle - Car pulls strong and smooth.
WOT - No fuel cut, pulled nice clear to redline, no boost taper. better overall.

There's your answer.
In all 3 conditions the car idled fine w/ no stalling.

I think Im just going to wait until I get the 3" TBE, fuel pump, reinstall the filter then get it flashed.

 

To you.... Thank you for putting an end to it.

 

Interesting results...