Clutch building pressure

[specialk2003]

For some reason my clutch is building pressure on its own. If I bleed out the excess pressure, it works fine for about 15-20min and then I start noticing the clutch is releasing higher and higher to the point of slipping. The clutch is not the issue and the master cylinder IS adjusted properly. The slave is new, and I have an S13 with a KA, stock clutch, and an ISIS stainless braided auto-manual conversion line.

Any ideas?

[gijoe69]

check the play on the clutch pedal such as adjustment sensors and the nut you turn