My clutch is making a squealing sound when the pedal is in the up position. If I barely touch the pedal it goes away. The clutch also engages pretty high on the travel of the pedal.
It sounds like you have a squeaky throwout bearing. This can be common on T-5 Mustangs. Just means it could use some grease. You could grease it, but this would mean removing the transmission. A great time to install a new clutch if you need one. As far as the clutch engagement issue, your factory cable may just be stretched a bit if it's the original cable. I remember that the Cable on my old '86 Mustang was stretched quite a bit when I installed an FRPP adjustable quadrant.
Engaging high on the pedal travel means there's very little slack in the cable (it's not stretched, at least not unless the slack was adjusted out of it).
Engaging high on the pedal travel means there's very little slack in the cable (it's not stretched, at least not unless the slack was adjusted out of it).