After cleaning the throttle body on a GM vehicle, you may need to perform a throttle/idle relearn. Performing a throttle relearn on GM throttle-by-wire vehicles can easily be done with the Mac Tools Mentor Touch Scout, No. ET6100.
For example, to perform a throttle relearn on a 2008 Silverado 5.3L, select and run the Idle Learn Reset test. Then start the engine and allow the ECM time to begin to learn. Additionally, the Mentor Touch Scout supports Throttle Sweep and Throttle Position tests to verify proper operation of throttle components. Throttle relearn can also be done without a scan tool, essentially by letting the vehicle idle in park for several minutes and allowing time for the ECM to learn. See appropriate service information for vehicle specific procedures and details if you wish to perform a throttle relearn in this way.
Information provided by Mac Tools