Have you tried taking it back off and greasing all the slides, pins and made sure the parking brake cable is working proerly? I'd at least try that along with resetting the adjustment screw (hand tight and back 1/4 turn). Be sure to use a high-temp grease on the pad slider clips and slider pins (both). No reason the BMC would cause a problem with one caliper o nthe rear (front maybe since their on seperate lines) and if the bleeding process was good with no debris coming out of the bleeder, I doubt is an issue with clogging in the line or dist. block.