Audi do fixed price clutch replacement, they quoted me something like 600, but think the DMF was more a tiny bit more on top.. Still very cheap for main stealer, you can always call for prices so you are armed
but I had a local place do it and I just sourced the DMF, clutch etc.. so was less than this. Problem was it couldn't of been diagnosed till it went as otherwise was healthy feeling.
Would be easier to diagnose a misfire on a petrol and cheaper (sparks, coils etc)!
As there are no spark plugs.. misfires on diesels as I understand is are more likely to be caused by faulty injectors, and they tend to be very expensive on diesels as they handle much higher pressure. Hopefully a knackered engine mount!
Really hard to advise online what it actually is, best bet is to get your hands on VDCS or similar to try diagnose it.