Our Ducato runs on natural gas, but has not been using petrol for some time. If you switch to petrol, it only jerks forward a few meters but then sips relatively quickly. When starting (what happens to gasoline) it also takes two or three starts.
My guess is that the fuel supply may not work. When opening the tank cap, there is often a clear hiss, as if there is a vacuum in the tank. However, I had the problem right after refueling, where probably almost no fuel was drawn. Somewhere I read that maybe what could be wrong with the temperature meter, but I could not fully understand it.
Does that give someone an idea? What could you try to track down the problem? Just change the fuel filter? That was probably last done 3 years ago, but in the meantime there was a rear-end collision, can it rust and cause these problems?