TDI Engine: Intermittent Power Loss - Troubleshooting

Hi, I have an Audi A6 with a 2.5L engine and 150 horsepower. After about half an hour of driving, the power suddenly drops significantly, and there's a strong smell of burning oil. Parts that have already been replaced: turbocharger, magnetic valves, pressure sensor. The ECU has a chip installed to increase the power to 180 hp, but test drives have also been done in the original state, and the problem is the same. If anyone knows what's wrong, please email me quickly. Thanks, Bernd.

First of all, a warm welcome. And regarding emails and such... well, that's not really encouraged here!

How about this: Have you ever looked into power loss and AFG (presumably a specific term or acronym)? I doubt it, otherwise you would have come across the following posts, among others:

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I think that's enough for now to quickly find the error.