P219B

The "Reduced Power" probably showed up due to the P2101. You have a drive-by-wire throttle body, I presume, so one of the sensors or actuator motors telling the butterfly and computer what to do when you smash the accelerator is not returning the proper range. Unfortunately, I do not believe the sensors your issue is with are replaceable without replacing the entire throttle body.

On an earlier model, such as my 2000 Silverado, you could replace the Throttle Position Sensor independently for ~$40. There were no brains controlling the butterfly, just a steel cable and your foot. The TPS told the computer what to do with the injectors and fuel mixture data, but not where to move the butterfly to. I don't know what the unit pictured below (including the throttle body beside the highlighted "brains") costs to replace.