noisy pedal & ABS light

[dumbjim]

I have a 95 windstar, and intermitenly, the brake petal will make a "spring- sprong" sound, when coming to a complete stop.
To make matters more confuseing, from time to time, the ABS lite comes on, on the dash , and the pedal, no longer makes the funny sound. Any ideas? The pads are all good,so is the fluid level, but I'm wondering if the problem might be in the power booster behind the brake pedal?
thanks,