pull up on the clutch pedal. if that doesn't work then you must have an aftermarket quadrant. if you have that you need an adjustible cable or firewall adjuster. ones you have them in its common sence to adjust it. the tighter the cabe the higher the pedeal grabs the clutch. the looser the cable the lower the clutch.
call up mustangs unlimited get the upr quadrant and firewall adjuster actualy drive down there they have them in stock there a pain in the ass but worth it stock quadrants suck