Brakes staying engaged, HeLp

1997 F-250 4x4

When I press down on the brakes then let up on the pedal it does not come up with my foot anymore. Brakes continue to be engaged and slowly disengage.
Master cylinder's fluid is full.

Who knows what could be wrong?
Thanks.

pinched line maybe,
is it front or rear?

Most likely a rubber line is collapsed inside, sliders need greasing, piston sticking, or rear shoes catching on the backing plate.
If it doesn't do it in reverse or releases from backing, it's probably the shoes sticking.

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i changed everything in my whole brake system. one part at a time, when mine was doing this. it was the master cylinder. it must be common, cause my bros 99 has been changed, my budies 99, and 03 have been changed also. i would bet $100 that your master cyl. is all rusted where the rod goes into the back of it. not allowing it to release. i spent alot of time and money chasing that problem, so i hope this helps.

Are you able to pull the pedal back up with your foot/hand? The pedal on my 94 was dropping an not coming back up. I threw a new booster in, problem solved.

My symptoms were similar on my 94 (brake pedal was delayed in return), but not as pronounced. Like powerstrokefirefighter, I replaced the booster and it solved it for me. Cheers!

Another possibility is that your windshield is leaking and water got onto the pedal assembly and rusted it. It happened to me. I took the pedal assembly out and cleaned and greased it. Problem solved. Not saying that is your issue but it is possible.