You can also try clamping the 3 flexible lines and see if that improves the pedal,if it doesnt its in the master cylinder.If the pedal does improve take off 1 clamp at a time and check pedal.This will indicate which brake is causing the problem.
Also when bleeding the brakes dont press pedal all the way to floor as seals in master cylinder can be turned on themselves.
Hope this helps.

Cheers FEWY