1988 Plymouth Reliant new brakes still not stoping

i had trouble with the brakes slowley going to the floor, i inspected it found brakes on frount were bad alsa driver brake line was cut i replaced all parts bleed lined ect... now it acted right for 24 hrs then the brake started to sink when you try to stop when it got as low as it could witch was about on the floor it would lock up the driver frount brake,the shortest brake line... when the car is off and you pump the brakes and hold they sink very slow i looked everywhere for leaks no leaks is my powerboaster or mastercylinder going bad? last time i bleed the brakes the passenger side would let out fluid then it would let out none also.....