At a random time the brake pedal will go to the floor but once i pump it it goes back to normal it did it last nite but came back it just did it a second time tonite but rebuilt pressure out of no were fluid is good no leaks that i can see im really stumped could it be a MC i really need to figure this out its a DD

 

Anybody

 

I would bleed them. I would guess maybe you have some air in the system or maybe the fluid is contaminated.

 

If it happens only when the brakes are hot, might be water in the fluid. It heats up and boils and you have no brakes until it cools again. More likely the seals in your master cylinder are about to send you on a not-fun adventure though.

Step on the brake pedal and hold steady pressure for a minute or so. What do you have?
Any sponginess? Does it slowly sink?