Could be anything, my guess would be EGR or DPF. Get it scanned see if anythings logged, as them to do a static regen aswell if you have a DPF.

Make sure you get as much fresh fuel in the new fuel filter as possible before fitting, enough to start it then immediately hold the revs at about 2500RPM for a minute or 2. If it wont start get someone to give you a tow start.