Blue_petersen77

I'm having a really odd problem here. About a week ago I took of in my truck before it was warmed up. About a mile down the road my pedal just went to the floor and didn't have any grab at all. After that she locked up normally and functioned like it should. Two days after that I had the same exact problem. I just figured it had something to do with the 20 degree weather.
Now just today the brakes got cosistently worse until I had total brake failure and had to use the E brake all the way home.
I bled all the lines including the lspv until all the air was out. I did this after noticing the release bolt on the bottom of the MC was loose and wet. Apparently a ton of air got sucked in at that bolt because the brake lines were FULL of air! I tightened the bolt and bled everything again.
Now I have intermittent break pressureabout every third time or so that I hit the breaks I get full grab, the rest of the time the pedal goes all the way to the floor with no pressure orit grabs a bit halfway down then loses pressure the rest of the way to the floor.
This is a really strange problem since it works sometimes then doesn't the very next time I brake.
I need some help here please guys. I'm completely stumped now! Thanks for any advice or knowledgable info in advance.

DJ99

The MC can fail intermittently just as you say. I would just replace the MC, rather than play roulette with the truck's safety. A complete brake fluid flush is a good idea too.

PLEASE, DO NOT TRY TO DRIVE IT!