Throttle/Pedal Position Sensor Issue Code P0123

I have an Audi A3 2006, and I am getting the code P0123 from the computer which is Throttle/Pedal position sensor A Ckt High Input. Can you please help me diagnose this problem?

Here is some history. For the last couple of weeks I had codes P2293, P0171, and P0222 coming on intermittently but especially after I filled up with gas. A friend of mine thought the issue was the fuel filter and we replaced it today. After replacing the filter, I cleared the codes and expected the issues to be resolved. The initial codes have cleared and not returned but now I have the P0123 code and the symptoms that the engine is not functioning properly remain.

Current symptoms: the power to the engine is not engaging when the gas pedal is pressed heavily.
My transmission seems to be okay because I can shift to all 6 gears in automatic, sport mode, and manual. As I start to drive my engine seems to be okay but as I continue to press down on the accelerator pedal I do not get an increase in power although I can hear my engine revving up. While this occurs the rpms increase but not past around 4000 although it sounds like the rpms are higher. I do not experience any shaking or other issues.