Had the same thing happen to my '96 a few weeks ago. Like FordNut85 said, check the bushing on the clutch pedal to master cylinder pushrod first. Could be a simple $.59 fix. If it's intact with no play, run down to your nearest auto parts store and pick up a new clutch slave cylinder & master cylinder for your truck. I spent $99 for both at O'Reilly Auto Parts. Easy to install with only 1 wrench, 2 bolts, 1 electrical connection, and a spring clamp for the slave cylinder. Follow the directions in the boxes & it's simple...took about 30 minutes to install & bleed the slave & master. Works like a charm!