I have a 94 civic and when I sit at a light the brake pedal will go from a firm pedal and then then to floor but still holds the car and then when I let go of pedal and press again I have pedal again or if I panic brake they work fine. Don't loose much brake fluid and have cheeked lines and wheel cylinders and no leaks. The only thing I have seen is a little wetness where the master cylinder bolts to booster and paint on booster looks like it's coming off due to brake fluid being on it. I think it the master cylinder due to that.