Diagnostic help.

[87GNSteve]

Odd brake problem.
Pedal feels normal when driving at cruising speed, stop sign/ stop light situations all feels normal. If I pump the brake or need to stop suddenly I get a hard(er) pedal. Panic stop distance is way too long and only locks up the DS front.
I have vacuum brake and swapped boosters as that was my first suspicion. I have excellent vacuum also.
I was thinking brake hose internal separation causing a check valve effect..... What do you guys think?

 

[TURBOTWIN2]

I think you already got it figured out (not counting the booster swap). You could raise the front end and check if one side isn't applying or not retracting when released.
If front brake hoses are original or very old, could be time to replace or upgrade to stainless. Also check caliper action: pins & rubber bushings, maybe stuck piston (doubt it).
Rears adjusted correctly?