clutch releasing?!?!

I have a 1985 GMC sierra, 305 with a 5 speed L,1,2,3-R and i am having problems with mt clutch releasing. when i press the clutch in and put it into any gear it goes in go nicely, but releases into gear with clutch fully pushed in. ive checked all the lines for the hydrulic clutch and there is no leakes. and when i am driving and come to a stop i keep it out of gear until i have to go so i put into gear quickly and when i release the clutch it seams to release fully when the pedal is only half released.......any answers?:disappoin

if the hydrolics check out to be good with no leaks or air in system
you may have a weak pressure plate
how old is the dlutch??

its the original clutch, my truck only has 140,xxx kms on it