Clutch concerns

For the past few days, I've been bleeding the clutch hydro's with a MityVac, which has been working for the most part. Sometimes the pedal is solid as a rock, yet at other times it has half the pedal travel of play in it; Like the slave has a good distance to travel to come into contact with the pressure plate. Could bleeding it even more more cure this? I know hydraulic systems adjust themselves, but is this the case with a good amount of travel needed or does it need to be shimmed? Everyone is telling me shimming is NOT the way to go, so that would be the last option. Most of the time, when the car is cold, the pedal play is more than half the pedal travel. Once it warms up, it starts acting how I've previously described.
Basically, I have bled and bled the hydraulics, but the play in the clutch pedal continues to move around. Any help is greatly appreciated!!
Rebuild it & it will be all good. I know thunder stocks the rebuild kits for like $30
http://www.thunderracing.com


