Front calipers are not releasing 100%. I discovered this issue while replacing the brakes, went ahead and did calipers, rotors, and wheel bearings while in there so I'm all new on both sides. Both sides will not spin freely and are heating up when driven. If I open either bleeder then they BOTH release...demonstrating it is not a faulty flex hose. Therefore it can only be: A) bad master cylinder, B) push rod out of adjustment (I did buy it used and have no idea what's been done), or C) a bad combo/proportioning valve.

I don't think it's an ABS issue, nothing indicates there's any failure there. I'm trying to avoid just throwing parts at it and would rather diagnose my way through the issue so I'm looking for a way to test each component listed above to see where that last few pounds of pressure is not being released.

I know for starters the push rod adjustment can be tested by breaking the master cylinder free from the booster thus creating slack. So that solves B.

Any suggestions on isolating that unrelieved pressure?