Hmm,sounds like a hydraulic problem,like air in the system or a faulty piston seal in the master cylinder.I guess that there are no fluid leaks?As you have replaced most of the hydraulic items,have a look at the clutch itself.Are all the plates and pressure plate properly installed?What about the push rod that goes through the motor,its not unusual for the pressure plate bearing to seize and grind the push rod down.
