Hi there!It sounds like a problem with either the clutch master cylinder or the slave cylinder.Check for any fluid loss at either location.It works just like your brakes and you are losing pressure someplace. Here is some info on the slave cylinder.
Disconnect the negative battery cable.
Disconnect the clutch slave cylinder tube from the clutch slave cylinder. Plug the line to prevent leakage.
Remove the two clutch slave cylinder retainers.
Remove the slave cylinder.
Position the slave cylinder and install the two retaining bolts. Tighten the retaining bolts to 12-17 ft. lbs. (16-23 Nm).
Unplug and connect the clutch slave cylinder tube. Tighten the tube nut to 10-16 ft. lbs. (13-22 Nm).
Bleed any air from the hydraulic clutch system.
Operate the clutch pedal and check for leaks.
Connect the negative battery cable.
Road test the vehicle and check for proper operation.
Fig. 1: Slave cylinder mounting-1991-96 models
Fig. 2: Location of the two slave cylinder retaining nuts-1997-99 models
HYDRAULIC SYSTEM BLEEDING
See Figure 3
Check that the brake master cylinder is at least 3/4 full during the entire bleeding process.
Remove the bleeder screw cap from the clutch slave cylinder and attach a hose to the bleeder screw. Place the other end of the hose into a container to catch the fluid.
Have an assistant slowly pump the clutch pedal several times and then hold the clutch pedal down.
Loosen the bleeder screw to release the fluid and air. Tighten the bleeder screw.
Repeat the bleeding procedure until no more air bubbles are seen in the fluid.
Tighten the bleeder screw to 52-78 inch lbs. (6-9 Nm).
Top off the brake master cylinder to the full line.
Check for proper clutch system operation.
Fig. 3: Attach a hose to the bleeder screw and place the other end of the hose into a container to catch the fluid-1991-96 model shown
The clutch master uses fluid from the brake master cylinder, might be your brake master is low on brake fluid.Thanks