Sounds like you put something back together wrong or didn't bleed it.
The clutch control system used on 1985---86 C and K models and 1987 R and V models consists of a clutch master cylinder, slave cylinder and a connecting hose. Pressure applied to the master cylinder pushrod from the clutch pedal forces the master cylinder plunger and seal assembly along the cylinder bore. As the plunger moves, the seal closes off the cylinder bore fluid inlet and hydraulic pressure is created which operates the slave cylinder. The slave cylinder, in turn, operates the clutch release fork through a short pushrod.
When the clutch pedal is released, the combination of fluid and return spring pressure moves the piston and seal assembly back until it reaches a stop in the bore. When the piston contacts the stop, the seal is behind the cylinder bore inlet (recuperation hole) and pressure is released from the system.
Inspect slave cylinder and clutch pedal travel.
Clutch pedal travel should be approximately 8.3 inches, and slave cylinder rod should have a minimum of 1 inch travel, measured at the clutch fork.
Inspect pedal bushings for binding and excessive wear, and the fork for damage, wear and proper lubrication. Replace components that are damaged or worn.
With engine running at normal operating temperature, hold clutch pedal approximately 1/2 from floor mat, wait approximately 9 seconds and move shift lever between first and reverse several times.
If shift is not smooth, bleed system and recheck operation.
If shift is still not smooth, inspect clutch components and repair or replace as needed.
BLEEDING CLUTCH SYSTEM
Fill master cylinder, as needed with new brake fluid conforming to DOT 3 specification.
Raise and support vehicle and remove slave cylinder attaching bolts.
Hold slave cylinder at approximately 45░angle with bleed valve at highest point.
Fully depress clutch pedal, then open bleed valve.
Close bleed valve, then release clutch pedal. Do not release clutch pedal with bleed valve open as air will be drawn into hydraulic system.
Repeat steps 4 and 5 until all air is evacuated from system. Check and refill master cylinder at regular intervals during procedure to prevent air from being drawn into system through master cylinder.