i have the same problem and have had mine diagnostic checked at ford and the problem stems back ultimatly to the fuel injection pump.when the light comes on your engine management system goes into limp mode and although your engine still runs enabling you still to drive the vehicle slowly you do lose top end revs-- there are various things that technicians can try before ultimatly changing the pump itself but the fact usually means you will need a new fuel injection pump sometime soon and all the other things just add to the cost and may not cure.-cost of new from ford is £1600 but a good fuel injection specialists can do the job for £600-£800 with a refurb unit. it is a specialist job in a nightmare to get at position so unless your a very good mechnic leave it to the specialists who have the tools, facilities, and test equipment to put it right quickly and with like for like parts as these can vairy greatly even on similar vehicles
jay
October 2011