Could be anything mate. Running rough could be caused by....spark plugs, leads, ignition transformer, build up of carbon in exhaust/throttle body, injectors, crappy fuel, oxygen sensors....the list goes on. For something like this though, I would definitely take it to a dealer. A dealership is the best place for a diagnosis. If the engine light was flashing, there may be a stored fault that the technician will be able to read. (I work in a dealership and always like external mechanic diagnosis. They get the 'problem fixed' at an outside garage and bring it to us when the issue re-occurs)