i think i know what it is, but dont hurt to confirm via a peanut gallery. so the truck has brakes, but the pedal goes straight to the floor with no resistance, removing the vacuum line impacts nothing and pressing it multiple times impacts nothing. now the fun part, when pressed it makes a whooshing sounds and air comes out he back of the booster.

its a 1994 f150 xlt 4x4

 

Not sure how you have brakes with what you describe, would be taking a hard look at the booster, though, followed close behind by the master cylinder.

 

Sounds like the master cylinder is bypassing fluid internally.
A bad booster would give you a hard, un-assisted pedal.

 

I have this exact issue have you found out what caused it

 

+1 for the master cylinder bypassing
Replace it
The noise from the booster is about normal
Especially on one that the pedal goes to the floor on
From the factory, there was some foam crammed into the rear of the booster where the pushrod goes in
That foam wears out and gets mooshed down, then the noise increases a bit
You can cram more foam in there if you want
I'd just leave it; the noise will never go away

 

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