I removed and blocked off the BAC valve. Turns out the hose going from the BAC to the i/c piping was loose enough to pull off by hand with minimal force. So I ran a T fitting with a vac plug on one end for the coolant line, and blocked off the other hose with a bolt and hose clamp. Tightened the hell out of them, and BAM. My car has a rock solid idle @ 750 now and no more boost leak! Very relieved it wasn't something more serious. Ok that is all.

Whoever said removing the BAC was a waste of time?