Hi folks! New here so please be gentle. This started 5 weeks ago!
Problem.......engine mangement light comes on above 70mph, engine feels rough (missing/hesitant?). Slight decrease in power until speed lowered and then everything goes back to normal (ie light goes out). Had the car from new, 225,000 miles and religiously serviced by myself. Absolutley no problems at all until now! No rattles, oil/water leaks or oil/water useage. Had local dealer read codes and nothing showed up, all he could say was that he recommended fuel and air filter changes! These were done promptley. Only just done 5k ago when the last service was done but still the same outcome. Can anyone help me diagnose this problem please....Gordon.