The brakes may be binding due to the pads sticking in the calipers. Yes make sure the steel lines are clear sans old coagulated fluid, dirt and or rust.

Since fluid comes out and you've replaced hoses etc. try loosening the master from the booster to see if the brakes release. It could be an incorrect MC, pushrod too long or the booster not releasing. Does the pedal work freely with zero binding?

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer