2005 Ford Ranger Edge 4.0L 4x4 ABS Extended Cab

I recently replaced the front calipers on my 2005 Ford Ranger due to a cracked piston. The brakes were a little spongy before this but not terrible. I flushed the brake system before putting the new calipers in to remove all the old fluid. I then installed the new calipers and bled the brakes from the rear pass, the rear driver, fr pass, and finally fr driver. Air bubbles came out of the system like normal and went away after bleeding. The pedal felt firm and short inside the vehicle as it should've.

When I turned the truck on, the brake pedal became very soft and long to press down. I checked all of the brake system for leaks and found a leak coming from the master cylinder, between the brake booster. I replaced the master cylinder, making sure to bench bleed it first, then rebleed the whole brake system with it installed. The brake pedal felt very firm.

I started the truck again and the brake pedal is still soft. I'm not sure if air is trapped in the abs pump or somewhere else, possibly, but I honestly don't know where to go from here. I can't find any info online of people bleeding the abs pump. The only other thing I think it could be is a vacuum leak within the brake booster, but I feel like that would make the pedal super hard, not soft. Thanks for your time.