Recently my clutch pedal has been acting up, with no obvious pattern. While driving i press the clutch in, shift to the next gear, so far so goo, but occasionally the pedal does not come back up off the floor. Sometimes it takes a couple of seconds, but it usally stays on the floor till i pull it back up with my foot. The weird thing is it shifts before and after just fine.

The clutch master cylinder has enough fluid. Is the master cylinder going bad, maybe the slave cylinder? Just air in the line? any help would be appreciated.

Thanks in Advance
Nik