I have had a master cylinder fail and this does not feel like that. I have to press the pedal about half way down to get the car to start breaking. Sometimes I do not have to do this. The brakes feel SOFT. Just got the car. It has 156000 miles on it.
Feels like air in the brake lines on 1997 Toyota 4Runner
Usually when a master cylinder is beginning to fail it will slowly go to the floor, but if you pump the pedal it will come up. But it sounds like air in the line and you need to bleed the system starting with the farthest wheel first