i've owned this truck for about 5 yrs and have always had this problem
intermittently the clutch will not disengage. driving along it shifts fine, but if i stop at a light and push in the clutch - sometimes its still engaged. i have to yank it out of gear. the pedal always feels the same - never soft or hard. i don't drive it a lot ( i live 10 blocks from work & have a motorcycle : ) ) in the summer but... at first i put a rebuild kit in the slave & master cylinder - same problem. then i bought rebuilt ones - same problem. then i bought OEM ones - same problem. i took it to a shop and had them re-bleed them - they said i did a good job - no air. i use new fluid every time i changed parts.
i took it to a clutch specialist - he said the fluid reservoir was clean and worked the clutch but couldn't find anything wrong. i asked - what should i do ? he stated he would replace the master cylinder again. i asked about the clutch damper (because i've never changed it) he didn't think that would cause my problem.
it's winter and i need to drive it more. what are your thoughts ? i've never been able to tell if it does it more when it's hot or cold. tonight i checked the rubber hose - fine and the fork pivot seems ok
tim