I too have HKS bovs. At first I vented them to atmosphere and tuned out the stalling issue with my AFC. I then added the recirc kit and I backed the settings out of my AFC thinking the stalling issue would be fixed. Nope. So I reverted back to my AFC settings and all is fine.
I'm guessing there is something about the HKS bovs that the car doesn't like. You are the only other person I've come across that has the same issue. Let me know if you figure it out.