Some SSRs have have issues with clutch pedal sticking. This is often due to the fluid in the lines getting rather old and clumpy. There is no drain valve on the SSR to allow a full flush of the clutch. Use a turkey baster or similar item and suck out the old fluid from the reservoir in the the engine bay. Install new fluid (Dot 4 Brake Fluid or Motul RBF600 ) and replace the cap. From inside the truck, pump the clutch 30-40 times. Repeat this several times until the fluid in the reservoir is clear. It may take a few cycles to get all the fluid out and running clear again.
Don’t let it get this bad before you clean it!