Grab your clutch pedal firmly in your hand and yank UP towards you. You should hear a zipping sound like a zip tie. This is the pawl on the stock quadrant taking out the slack in the cable. Now try working the pedal and see how it feels. Not saying this will fix it but if your cable is stretched over time that could be it. Although generally a stretched cable will mean it won't start to engage at all until it gets near the floor, not up top.
If you DO replace the cable, DO NOT USE A PARTS STORE CABLE. They are NOT the same as an OEM cable and they WILL bind and usually snap after not too long. You want an OEM style cable which you can get from Maximum Motorsports or your local Ford dealer.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.