Driving vehicle at highway speed, engine RPMs dropped to less than 1500, could not maintain any speed, CEL illuminated. As soon as vehicle was pull to side of road, it would no longer run. It would start, idle roughly then stall out. Vehicle was towed to Mountain Hyundai in Denver. High pressure fuel pump failed, fuel pump in one cylinder failed, fuel was dumped into oil fouling all spark plugs. This is the second high pressure fuel pump failure on this vehicle.