why does the break peddal intermitently go to the floor?

What is your question?

break peddal randomly goes to the floor most of the time the peddal is firm and the breaks work great, but then out of no where the peddal will go soft and to the floor. I have manualy bled the brakes and tried doing an auto bleed with a scan tool, but the auto bleed fails because the vehicle is in motion, even though it is in park in the driveway.