That’s weird they keep trying to replace the throttle body, even though it’s not solving the problem. That sounds like an electrical issue to me, like a bad ground or a short in the wiring. I’ve had luck troubleshooting this type of problem by grabbing the factory service manual, figuring out which ground is used by the malfunctioning sensor, then tracing that back to a single ground point.

There’s a good chance that ground is dirty or corroded. I’ve even had this happen on a 4 year old car. In my case, when I figured out which ground I needed to check and opened up the connector, it was pretty easy to tell the ground was slightly corroded. Cleaning the ground solved an intermittent issue I had with my pedal assembly.

I would suggest to the dealership that they check the ground(s) used by the throttle position sensor. It’s probably a chassis ground in the engine bay.

How long has it been since the motor was replaced? Perhaps you could take it back to that shop and have them check it over. I’m guessing it’s a sensor or ground issue with the throttle position sensor or accelerator pedal sensor.