Pedal Position Sensor Issue

Driving out of the mountains today, our 9-3 suddenly flashed on the check engine light and TCS OFF light simultaneously. I could hear a relay clicking from somewhere behind the dash. The car would shudder hard once it hit just over 2000RPM from that point on (I assume this is a "limp home" feature). The car also would shudder when stopped with the car shifted into drive, but was fine in neutral or park. We made it home and to a parts store. The code reader spat back

P1530: Pedal position sensor 1 and 2 circuit sum out of range.

Does anyone know what this is and where I need to begin trouble shooting? I would like to avoid purchasing a new throttle body if at all possible.