New Flywheel - New Problem

[pctvscol]

hi all i recently have had a new flywheel and clutch fitted on my 06 focus estate 2.0 tdci , problem is i have a juddering and feels like loss of power and its random even at 30mph or 70 mph or simply just pulling away from junctions . i am not 100% its anything to do with the new flywheel and i asked a mechanic when i had a service recently to look at the fault codes ..........he did however say somthing about a overfuel sensor and to drive the car at 3000rmp for about 20 mins in 4th to try clear it which i havent done as i think id just rather pay for what ever needs doing ie a new sensor ..............can anyone shed some light on this id be most greatfull.......thanks in advance