Yesterday it was completely fine. Today not so much. My clutch is very stiff and I can't shift it into gear. When I let up on the clutch (when it is started} and in neutral it almost hops forward. I can not shift the shifter into any gear while the jeep is running, but it slides right into gear when its not running. A friend of mine said maybe the slave cylinder or someone also said the clutch has gone? Any info would be helpful.