How do you know if it is the Electronic Throttle Body or the Fuel module?

I would check the recalls first. The situations I have had with Chevrolet, Nissan, and Chrysler is the communication between the pedal and the throttle body. And 98% of the time was the throttle position in the pedal. With Chevrolet I had to replace the complete pedal assembly which is assembled all together, (the sensor, pedal, and mount), for example.....