The fact that you have no misfire, O2 or other codes makes me think it's either the sensor in the accelerator pedal or the mechanism in the throttle body. The fact the ECU does not see a problem indicates to me that the pedal sensor is simply not telling the ECU the truth about pedal position or movement.

I"d lean toward the pedal first, myself. Changing it means changing the entire pedal/sensor assembly and its not cheap - but it IS easy to do.

IF that does not do it, I'd change the throttle body.

I am not convinced the evap system can do this, I've had P0453, back when the ground pin of the sensor connector got all corroded because I (oops) washed the car with the top down and was not as careful as I thought it was. THe car ran fine. (This was on my first 2005 Roadster, years ago.....)