Sounds like fuel a supply problem, If it runs O.K. and starts to run rough when you want some power there is not enough fuel pressure or flow, Filters are the usual suspects. I always start with the least expensive item, clean and change. If you have a manual check to find all of the filters. Regards John. Sorry I meant to say even if it turns out to be a pump fault this work still needs to be done, as restricted fuel supply can damage a new pump.