Hi; If your vehicle has a catalytic converter, it could be the source of your problem. Catalytic converters (and rarely, mufflers) can break up inside and plug off the exhaust. When that happens, you'll experience the severe loss of power. When you stop or turn off the engine, the plug may fall away and then be 'fine' again. This can be checked with a pressure gauge attached to the upper oxygen sensor fitting.
I have a Ford Figo petrol 2010 model in india. I am facing an acute problem since 6 months. While the car is running normally at times the engine diagnostic light in the dashboard glows and the car speed doesn't increase beyond 20kmph It happens as if the power output has reduced to half.
But after restarting the car the symbol disappears and the car runs normally.This issue occurs frequently with no set pattern or condition of running