Do passenger cars have the equivalent of a race car's "brake bias" dial? Like maybe an "equalization" valve, or something? What about your right side brake line path -- could it be "plugged" such that the left side grabs harder than the right? Is there a way to check the caliper braking "force" that's applied to the rotors?
How about the rear tracking rod or pulling strut bushings?
I know this doesn't solve your problem, just throwing a few more questions out there so maybe we can all benefit from the answer(s).