Yaris Soft Brake Pedal Problem

[xdarkxfirex]

I thought before it might be a master cylinder problem since I owned the car. Replaced a few of those on this car, and returned the aftermarket ones I got, both centric and dorman. I then used the original New advics brand toyota uses last month. Seemed to be the same. The car does stop and holds pressure but sometimes I feel like I am loosing pressure If I hold the brakes, when stopping. It could also be brake fade. I could press on the brakes and feel like it engages and then doesnt as hard as it did after a second or two. It doesnt inch forward at stops, or sinks when stopping, so I guess it should be fine. Usually a bad master will sink regularly, but I am just paranoid. All my OEM rubber hoses are still fine. No cracks yet.