I had exactly the same problem. I took it to the local ford dealer (still under warranty) and got 3 new starters and 1 rebuilt starter put it over the course of 2 years. The problem happened again about last year so I took it to my mechanic who installed another rebuilt starter. The next day it wouldn't start again so he checked everything and discovered the negative wire off the battery had never been completely tightened to the block. It had just about burned off the connector. He installed a new wire and there's been no problem since.
94 Laser Red GT, Explorer intake, Hedman shorties, Crane 2030, Diablo custom chip, MAC H-pipe and cat-back, Bullitt rims, Steeda lower arms, boxed FMS uppers, Cobra brakes, Koni StrT struts & shocks.