You can "degas" many fluids with a mightyvac, just get a good seal on the litte container they give you and pump as much as you can. I used that method to degas resin before I poured it into a mold. There is a video on a resin site that shows a vacuum pump doing this, it pumps and all of a sudden all these bubbles appear and rise to the surface, in essence boiling them out without heat. I dont think the spongy pedal is the fault of the air, I bet its your seals not designed to work with DOT5 fluid.