Unless you have extremely bumpy roads, this throttle behaviour appears to be totally abnormal. This seems to be backed up by Heinz’ experiences in a similar model. Following his advice, before wasting money on pedal plates etc, I would strongly advise that you look first to see if it is indeed “fly by wire”. This means that there is only an electrical connection between the throttle pedal and the engine compartment, instead of the traditional bowden cable. If so, then I would strongly suspect a faulty or loose throttle position sensor.
