I believe that I need to replace the clutch assembly. My truck revs up a lot, but has no torque or acceleration. I need to accelerate very slowly and I think the clutch disc is worn out.
From your description, it does sound like a worn out clutch. The clutch has a friction material much like brake pads do. This material wears out over time and symptoms like the ones you are describing are typical. The clutch is usually replaced as a unit with a pressure plate, slave cylinder, throwout bearing and pilot bearing. The flywheel is sometimes also replaced or resurfaced depending on its condition. This is a repair that should be performed by a qualified technician. I recommend having a qualified mechanic inspect your vehicle’s acceleration to determine what exactly should be repaired.