TDi Fast idle vibration

[SBateman74]

OK so this might be a simple case of "it's a van"...however...

I picked up my 2017 2.0 TDi caddy on Friday and have done a couple of hundred miles over the weekend, mostly on motorways and its been a pleasant surprise.

The one thing that's spoiling the experience is at the when the engine drops to around 950 - 1150 rpm the van resonates, is this normal ? When out of gear it idles fine at 900rpm it's just when you put the clutch in the idle speed increases slightly and its at this point the resonance occurs, the same when changing gear as the revs naturally drop to the same point.

Is this normal? If not any ideas ? Could it be fact its mapped ?

Thanks