Truck revvs engine instead of accelerating?

I have a '97 Nissan Hardbody Pickup. 2.4L / 4 cyl. Whether I'm simply starting to drive from a complete stop or attempting to accelerate as I'm driving, my truck's RPM increases without the truck itself accelerating. The only way I can accelerate is if I very slowly press on the gas pedal, and sometimes not even THAT works! Will replacing the clutch kit and flywheel fix this problem? Or will something more be required?