Soft Brakes

[GlassHeadlights]

Car: EG Civic coupe Si non ABS

Brakes: DC Integra GSR ABS booster/master + rear discs approx. 200K miles

The car will stop shaply but the pedal sinks to the floor slowly. I've bled the system countless times and there is no fluid loss.

Do I need a new master cylinder?

 

[Matts96HB]

Checked for leaks near the master cylinder? Even small ones could cause the pedal to go soft like that.