CaNaDa Stang

i bought my 94 GT Mustang 4 months ago and i noticed the clutch was squeaking so i put a new clutch kit into it. the squeaking continued so i parked in on my friends pit and took off the clutch fork cover and noticed that the clutch fork was vibrating way more than the tranny. If you hold the fork the squeaking goes away i was just wondering if anyone had any idea what is wrong? O and the guys at work tell me [work at a NAPA store ] the clutch had been replaced 3 times and 4 new throw out bearings have been put in