Are you loosing any brake fluid? Does the car have ABS?
Might be the master cylinder is getting an intermittent leak. There might
also be crud in the fluid. It's a good idea (since brake fluid absorbs water
and goes bad) to flush out the entire brake system with fresh fluid every
few years. Open the right rear brake bleeder and put a hose on it and into a
jar of brake fluid (or use a check valve) and pump the brakes slowly. Just
don't want to suck air back into the system. When the reservoir is nearly
empty, fill it with fresh fluid and continue pumping until you get clear
fluid at the bleed end. Keep adding fluid and bleed remaining brakes untill
you get clear fluid out of all the ports..
Maybe you'll get lucky that it was a rust flake that was keeping the piston
from sealing completely. Oh, and be sure to use the manufacturer's
recommended fluid (DOTx) to protect the seals.

"John Doe" > wrote in message
...
> 1993 Saturn
> Myabe one time in 20 the brake pedal will go way low, orherwise they are
> good. Normally don't have any pull or anything, no clue. Any idea what
> this could be or any way to isolate the problem?
> Thanks,
> Dave
>
>