Ford focus 1.6 diesel econetic engine..... Had a problem with EGR cooler as it sheared off from egr but have replaced.... Now a new problem, when the car reaches around 2500 rpm if under sharp throttle the car starts to judder and jerk sometimes splutters too and sometimes the revs dip up and down via about 200rpm whilst juddering... also has been serviced and used dpf additive and there is no check engine light also the car ran okay when the air was by passing the cooler but now a new one has been fitted this problem has started to occur... please help asap thanks....

I know you said it's been serviced but when was the last time the fuel filter was replaced?  I understand a blocked fuel filter can cause hesitation issues .....

Changed fuel filter just over a week and the car has done about 100 miles since then.... We changed the filter and then added the dpf cleaner then took it for a drive thinking it was a dpf issue.... was okay for about 4 days then the jerking started again.... sometimes it's okay then the juddering started out of no where and another thing.... when the car is running okay the revs idle just above 920rpm but when the jerking is happening it idles bang on 920rpm so does drop some revs but im almost certain it has some thing to do with the egr cooler as it was okay when the cooler was broke but now it's fixed this has started to happen 

And the egr itself has been cleaned and so has the throttle body and a little bit of the inlet there was a fair bit of carbon build up on the bit of inlet visible when the throttle body is dismounted