Brake question

[performancelaw]

When I apply the brakes the pedal is kinda soft. I can pump them and get them firm but as I hold the pedal it slowly goes soft. Truck still stops fine just has a softer pedal them I'd like ? Thank you for any help.

 

[91idi]

Leaks at master cylinder leak, lines, drums, or caliper. Also try just bleading them

 

['94IDITurbo7.3]

I just went through all of that and still have the soft pedal.
I replaced every single part in the brake system except the vac. pump and the booster.
I bled about a gallon and a half of brake fluid through the system and still no better.

Hope you find a solution. I f you do please post it up.