Soft low brake help

Sisters 04 Aveo had a sudden drop in brake pressure. Discovered a slight leak at a rear wheel cylinder, but not enough to justify the loss. Replaced both wheel cylinders and the Master cylinder. Bench bleed the MC first, then bleed the entire system. Several rounds of bleeding later (some with the mityvac and some with an assistant on the brake pedal) I never see air bubbles, but the pedal is still way to soft. I've cleaned every part of the brake lines, there is no leek anywhere. I adjusted the rear brakes out far enough to drag just a bit. Before I give up and tell O'Reilly they gave me a bad MC, does anyone have any ideas here?

Are your wheel cylinders in right? the bleeder should be above the brake line.

Are you going in the right order? passenger rear, drivers rear, passenger front, then drivers front, repeat.

Does the car have ABS?

Oddly the GM service manual I have calls for RR, LF, LR, RF. But I have tried both. No ABS. Just used rags and vise grips to carefully clamp off each rubber line. Hard as rock, so I know the MC is both good, and fully bleed. I then un-clamped one line at a time and bleed ~1 cup per fluid each using an assistant. No appreciable difference, and no one of the 4 lines seems softer than another when its the only one un-clamped. As I un-clamp then its just a cumulative lowering and softening of the peddle. Loosing my mind here, this aint my first rodeo, but it sure feels like it. What could be wrong, or what stupid think could I be doing wrong here?

I finally got it. I was calling the front pads good enough for now, but when I put digital calipers on them they were just under spec. Replaced pads and rotors, which of course pushed the piston all the way back into the caliper. That reduced pedal distance a lot, but it was still squishy. One more bleed round and I got a big bubble out of each front. Now its back to normal. What a PITA!