My oldest son drives a 2006 Jeep Commander Ltd, 5.7L Hemi.
Has just over 200,000 miles now.
Front brakes started making noise the other day so we decided to put new front brakes on today (Sunday, 7/30)
Pretty normal brake job, rear disc pads are over 50% so we left them alone and went to the front.
Pulled front calipers and pads were very worn (about 10% left) so we repalced the pads. On the LF, the twin piston calipers had a piece missing off one of the pistons (chunk broke off). So, we bought new calipers at Auto Zone (close to our home and open on Sunday) and installed. Since we opened the hydraulic lines, we installed, topped off brake fluid and manually bled all four wheels starting with the RR (farthest away from the master cylinder). Bled just fine, got a little air out, sprayed a lot of fluid, closed 'em all up and topped off fluid.
Pedal is spongy at best, and occasionally goes all the way to the floor. Couldn't figure out why, so we started over, checked for leaks (none) and re-bled the four calipers. When we got to the RF, got a lot of air out of it before the fluid started flowing. Tightened everything up, same condition.
Pedal is still spongy and still goes to the floor every third or fourth stop. ?? Now it's raining (we were working on it outside) and we are both at our wit's end.

I feel like I'm missing something simple, but just so frustrated that I'm not seeing it.

Any advice appreciated. Thank you!

JS