2003 Suzuki Vitara brakes failing

I need your Help,

I have a 2003 Suzuki Grand Vitara, about 45,000 miles. In the past year I have had four incidences where the brakes have failed.
Each time.

With in the first couple miles of driving.
Happens at very low speeds.
Brakes get mushy and go to floor.
Most important. The engine races as I apply brakes that will not work.

Third time this happened I was parking and the car jumped a curb before stopping and hitting another car.

Fourth time I hit a car at a stop light. I was going very slow.
AND NO MY FOOT WAS NOT ON THE ACCELORATOR

After the third problem I had the master brake cylinder replaced. It was a shot in the dark but the only solution the mechanic could suggest.
Please any suggestions, ideas?
N6kzw@sbcglobal. Net