Did you do all the work yourself or did a shop do it?. What year is the truck I assume 1992 to mid 1994. I have never had a master fail just the slaves, and always traced back to something wrong with the pivot ball. My 1993 has an access hole (small one) for greasing and with a good flashlight you can observe the action of the thow out arm etc while someone else pushes on the clutch pedal. IF all the parts are correct and installed by you I suspect the throw out bearing may have come part way off the throw out arm. Does greasing it make a difference?
Al
Original D.P. Member #750, 2009 Ext Cab LB 4x4 Duramax/Allison, Black, Linex, 1993 6.5 TD 4x4 reg cab LB, 5 speed, 1972 Pontiac Lemans, 94 cady De Ville