Check the two 70 amp relays for the glow plugs, may sound silly but glow plugs also burn off excess fuel which can cause the juddering. If one relay is duff the ECM shuts the other one off for safety but still allows cold starting.
Just had my mate who has Autel Diagnostic kit do some updates following new fuel filter change, still had low speed acceleration juddering, system shows that glow plug relays not working, discovery 3 has two 70 amp relays and if one fails it...