Most cars that have drive-by-wire TB, have some sort of process to relearn the throttle valve position after the TB has been replaced, cleaned, or the battery has been disconnected. Your car looks to be exhibiting symptoms of an incorrectly learned throttle position. Dealerships have proprietary diagnostic equipment that force a throttle relearn.
Since most DIYers and independent garages don’t have access to said a equipment, the ECU usually contains some form of manual procedure for forcing a relearn. It’s typically some sequence of turning the ignition on and off, and holding the gas pedal at various positions. That sort of thing. You might want to see if you can track down the procedure for your ride and give it a try.