if the engine management light is on,you could be causing signifacant enginge damage.there are hundreds of faults on new cars that can cause the engine management light to come on and cause hesistation through the speed range.I am afraid your gonna have to bite the bullet and get the vehicle on diagnostics to see what exactly is the fault.you do not have to go to a ford dealership now to be put on diagnostics any repituable garage will have diagnostics to do the job.
john howatson, September 2008