Any symptoms the truck is doing?

I'm confused.

P0121
Throttle Position Sensor/Switch A Circuit Range/Performance Problem

http://www.troublecodes.net/OBD2/Pcodes.shtml

I'm confused too but symptoms would clear things up a bit too.

Wondering if it is hesitating at all or reving high or irratic thru different throttle positions.

I would go ahead and clean throttle body and replace the TPS which shouldn't be much.

Well Im confused too since Auto Zone told me it was an Evap system code. Dont have any symptoms at all other than my gas mileage has seemed to be a little down over the last year. I just contributed that to E-10. The code reader I used was an el cheapo I will try Oreileys or somwhere else and see if I can have it read there as well.