A4 2.0TDi judder when warm

[Phil3000]

Hi, I'm wondering if anyone has any suggestions. My car has just been in for a new DMF and No 4 cylinder glow plug. It's needed this for a few weeks and I have been limping around waiting to get it done. Now it's done the car is perfect until it has warmed up after about 15 miles. At this point it starts to judder between 1500 and 2000 revs. The judder is very pronounced. It could be that the problem is as a result of what's been done - not suspecting DMF, but possibly glowplug replacement as it feels like an engine misfire rather than something being out of balance. It could equally be something that was there before and I hadn't noticed it as I've been limping around for a few weeks. I have a basic code reader and nothing is showing. Maybe the diagnostic kit available to the pros will show more. I'll be going back to the garage, but like to be able to talk inteligently rather than be bamboozled by what I'm told. Does anyone have any ideas?

[annodomini2]

Which engine?

[Phil3000]

It's a BRE engine. Also, I forgot to mention, multitronic gearbox, although I don't think that's the problem.