If I remember right, the clutch slave cylinder is part of the throw out bearing, and should have been replaced with the clutch. All this only applies if there is a hydraulic clutch. Check the reservoir for fluid and try bleeding it properly. use a clear plastic bottle(soda bottleswork great!). have a small amount of brake fluid in it. Open the bleeder screw, install a 5/32" hose on the bleeder and submerge the other end in the fluid in the bottle. Slowly pump the clutch pedal, having a helper watch the fluid level in the bottle. When there are no bubbles coming from the hose, and the fluid level rises, close the bleeder screw and try the pedal. It could also be that the clutch master cylinder has gone bad. If that's the case, the fluid level will very slowly rise while pumping, or not raise at all.