clutch pedal at end and depends on temperature

[coupesx97]

Hi Guys

For Some time my 97 rd2 tib clutch engages at the end of the pedal travel. And on Hot days " 40deg" the clutch starts slipping because the pedal wont release it even at the end of the pedal travel.
If I go and relieve the fuild at the slave clyinder the clutch will fully release. Its lie the master/ slave is NOT letting the clutch fully release.
I replaced the slave cylinder, as it was leaking fuild. But the same thing is still occuring.

Any one else encountered this?

Cheers
Brett