powertrain warning light when pushing over 2800 - 3000 RPM

I have a FORD FIGO 1.4 L diesel , the car runs good under 2800 RPM but when I push it over 2800 or 3000 RPM the powertrain warning light starts blinking with sudden power loss, after restarting the ignition the light goes off and come up again if I cross 2800 RPM, it used to go upto 4300 RPM earlier. 

could you please suggest what could be the issue ? 

Now the engine is very noisy i am not getting any change in fuel efficiency,