[SPF2245]

Intouch, not trying to second guess anything you've already tried, but try bumping up the idle on the motor to build more vacuum. It's a cheap fix that worked to make my brakes more usable when the motor was near idle (Roush 427R). When I lowered the idle too far (about 950), it really did a number on the brake pressure available. I just kept upping it a few hundred until I got not only more brakes back but could kill the motor w/o the motor starting to "diesel" when turned off. Just a thought, and if it doesn't work your not out any money for trying.