bleed the system first and see if that helps.. another thing is to check around the master and slave cylinders to make sure they're not leaking.. the smallest leak will cause a problem- it honestly sounds like your slave cylinder is bad.. the slave is (in my car anyway) the part that pushes and retracts letting the clutch engage and disengage.. if that TOB is not moving, you're not getting any pressure on your clutch- making you have to push it hard to the floor in order to get some movement. is your slave/TOB original to the truck?