How to fix Nissan Almera tino 2.2di low revs acceleration problem?

Recently my almera tino 2.2di has been juddering between 1200-1800 rpm.Feels like the diesel is not been injected properly.When you rev the car in neutral between these revs it puts out white or clear smoke.I have just had the air flow meter (maf) changed but it still persists.
Has anyone got an idea?