Hello, I bought a piaggo nrd 50 used, two days later the moped gives gas on its own. And partly when I give gas. On the steering wheel the engine works off. Starting it always does, because the spark plug is new. It also happens that the moped when this phase comes, that it gives gas on its own or the speed over 4000 comes the moped does not react to the gas from the steering wheel. It happens then also that the engine throws off these problems, but also only timewise e just before at the beginning of my ride. Does anyone have an idea what to do?