Why would the throttle stop working on a 2003 Chevy silverado with a 4.8 v8 ?

Hi Richard, IM AL the owner of Big As Auto Repair!

Richard, if the check engine light is on have autozone check the code, if the code is for the throttle pedal then you need to have it checked to see if its the pedal assembly or the throttle body itself.

I can tell you by history of working on these that most of the time it's the pedal assembly but not always. Its up to you if you take the change on the pedal or spend the money to have it checked to make sure which one it is. Hope this helps and please visit my auto-repair-website: http://www.bigasautorepair.com/

Http://easyautodiagnostics.com/gm/4.8L-5.3L-6.0L/app-sensor-tests-1

Hope this helps...