Yeah that is weird... Well, start with the small stuff. These cars are old nowadays and if the original quadrant/cable are in there its a good idea to get the whole Max Motorsports kit and replace everything. Should be done regardless as a preventative thing at this point.
For a quickie shot in the dark at fixing this, go grab your clutch pedal with your hand and yank towards you HARD. If you have the stock plastic self adjusting quadrant, this will take out any slack in the cable.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.