Had a similar issue with my 3.7 Roadster Dave. I was leading a tour group in North Yorkshire. Symptoms were severe misfiring on small throttle openings, fine idling and with foot down. Absolutely nightmare trying to get through villages with engine rapidly cutting in and out. Wiggled all relays after I had chance to stop and restart later everything was fine. Once home I replaced the ECU and Fuel Pump relays with Durite equivalent. No issues since in close to 10,000 miles.
