Time, wear and extended competitive driving in your 1984-1988 Corvette with a manual transmission will eventually take its toll on your Clutch Slave Cylinder, causing shifting problems.
Replace your worn C4 Corvette Clutch Slave Cylinder, Clutch Master Cylinder or Hoses to get the clutch response you deserve. If your clutch goes to the floor and doesn't return all the way, if you have little or no resistance when pushing the clutch pedal, or you can't keep fluid in the reservior, then the slave cylinder is a likely candidate for replacement.