1G REAR BRAKE ISSUE

[o0GuitarKid0o]

Okay so somthings wrong with my rear brakes,
In order to stop i have to pump my breaks Atleast twice to stop .
How do i know its my rear breaks? Well its winter so i went in a parking lot and got my buddy to watch my tires as i hit the breaks once, my fronts lock up while the rears spin unless i pump it than all four stop

Heres what ive done to try and fix it
Replaced master cylinder (bench bled) and bled it on the vehicle to make sure no airs in the cylinder
Bled my rear breaks starting farthest from the master cylinder
My bleeders screws arent working properly because fluid comes out of the threads not the hole guessing its clogged?
Clean fluid did come out eventually

E break works excellent as usual so the caliper is not sticking

Break pedal goes to the floor on the first pump then gets hard after a pump or 2

Vaccume booster works no leaks under the break pedal either

The check valve works in the vaccume line

Only thing im not sure how to test is the porportioning valve

None of my lines are leaking
Calipers are dry
All my breaks have been replaced and lubed in the last year
Any ideas?
Could it be a bad rubber hose on the caliper?

Im by mtself today so prob going to remove the bleeders and clean it and let gravity bleed my breaks

1991 plymouth laser rs turbo with single piston calipers the ebreaks built into the caliper

 

[HIGHPSI4]

Break pedal goes to the floor on the first pump then gets hard after a pump or 2

Still sounds like a master cylinder issue.

 

[Dsmkauai]

You still have air in the system somewhere. I would take the bleeders off and either clean them out or get new ones. Then try bleeding the brakes again. If it still does it after that then there's a leak somewhere and it's sucking air in. It could be a clogged up hose and it's not letting you bleed all the way.