2003 GMC Sierra check engine light, reduced engine power

I had a computer diagnostics check on the engine and received the following information:

Definition: TAC module throttle actuator position performance.

Explanation: The ECM has detected an out of range condition between the predicted and actual throttle position.

Probable causes:
1. Poor connection at the TAC module
2. Failed TAC module
3. Check TPP or TPS sensors
4. Binding or bent throttle plate-failed throttle body.

Can you provide some help as to what exactly I need to be checking for? And where can I find schematics for the above problem?

Your help is greatly appreciated!
Joe