How do you replace a bad tie rod on a 1998 F-150?

By experience, unscrew the nut on the center drag link until off, you may want to mark on the center link where the nut was (if not I hope you have access to an alignment rack); secondly remove cotter pin from top of bolt on the head of the tie rod and remove nut. With the next part you may want use a pry bar or hammer to get the head out. I caution using the hammer as the bolt head may mushroom an not allow you to remove the bolt.