1999 jaguar xk8 fuel problem this car wants to die we have already replaced the fuel pump has plenty of fuel pressure we checked the coils its fine when its running around 40 mph any suggestions?

have you had the throttle body recall done? Not sure if it is in effect for the 99, but the 97 it was, and this helped fix an issue that many people had when nearing or at highway speeds the engine would die randomly. I'd research that. Call the dealership with your VIN number and they'll be able to tell you if it's been done or needs to be.