I need some brake help please

[nychevyman]

i did one more test today when the pedal is stuck to the floor I pulled the vaccum out and the pedal pops right up.
the truck was running but cold blooded, when it idled down the pedal would rise and when i gave it a little gas to keep it from stalling the pedal would suck back down to the floor??? I did it ten times to watch it. it would go up and down

I showed my Dad and he had never seen that before.