1996 Ford Windstar Antilock brakes puls when not required

There is probably a speed sensor going bad at one of the wheels. If it sends a signal different from the other 3 wheels, the interpretation is that it is in a skid and pulse them. May have to have a scanner capable of reading the signals hooded up while the problem happens to find it.

This may also be caused by a cracked abs ring or harness or bcm problem.