Sometimes when I step on the brake peddle, it will almost go to the floor with no braking. I quickly release the brake peddle and it comes back up, then I step on the peddle again and have normal braking. Very strange (and attention getting). It happens very infrequently, like once a week or every other week. Any thoughts about what is causing this problem? Thanks for the help.

Check your fluid level, and then bleed your brakes. I had a similiar problem, only it was all of the time. It's not safe, so you need to find out the problem and get it fixed. ;) If that doesn't help, you could have a seal on one of your drums that has come loose. That was the solution to my problem. If all else fails, check all of your brake hoses and connections to see if there are any leaks. Hope that helps, and Welcome to the Forum!

Could also be the master cylinder. When the seals start to go bad, the fluid seeps back into the reservoir. This would cause the same symptoms that you are having. If you are not loosing fluid this is probably the case, but if you are loosing fluid then do as Figori recommended.