I've got a 1999 F-150 4x2. The brake pedal on it is verrrrrry soft and touchy. The brakes seem to be working fine but in a panic stop it seems as if the pedal goes almost to the floor. I have no idea if or when the brakes were last worked on, I got the truck at 82,000 miles from a dealer on a trade in and it now has 92,000 miles. The problem hasn't gotten any worse. I have driven my aunt's 2000 Expedition and her brake pedal is much firmer.

 

Start with some basic maintenance. Bleed/ flush the brake fluid. If you're unsure how to do it, then take it somewhere to have it done.