'91 TC executive.

For some reason when I hit my brakes on occasion the ABS kicks in then when I let off the peddel and reapply pressure its fine. Whats going on?

On the Mark VIII the ABS is activated when the ABS module senses a wheel is about to lock up, based on a signal it recieves from a anti-lock sensor at the wheels. Most faults get stored as a trouble code in the ABS module that you can retrieve for trouble shooting.