Juddering issues

[kev75]

All,
New to group and hope you can help with a little advice. I have a 2011 2.0diesel blue motion passar estate. Let me expand on what has happened recently.
1 - engine was juddering at start up which I thought may have been fuel restriction but I'm not a mechanic. Issues go and car revs normally after about 10 mins / when getting warm
2 - glow rods replaced under warranty but issues still there
3 - fuel filter replaced but issues still there
4 - further issues, until warm engine would not exceed 2500 rpm and running rough. Lots of engine noise, White smoke out of back
5 - injectors sent off for independent investigation, 2 of which had a slight intolerance I'm told, suspected fault symptoms and potentially overfueling, sensors unplugged and runs rough but not as bad, a particular test was run which led to fuel coming out of the exhaust
6 - I have been told that the fuel is suspected to be contaminated ie will light where as diesel will not. Categorically never put petrol in my car. Does not explain why issues go after 10 mins but return the next day. Told this may be because the car is warm. Car is regularly filled up so tank would be regularly flushed or diluted if contamination was an issue.
7 - the fuel tank has been drained, the system flushed and new diesel added.
8 - told extensive road test performed with no abnormal noises, no further smoke and performance is as expected

I am not sure what has caused the issue. Car keys won't be returned until I have taken a test drive to see if the issue returns. Unsure where to go with this now. Are there any other things that could have caused the issues, has anyone seen or experienced this themselves.

Any help or advice you can give will be greatly appreciated.

Thanks!

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