Jerky movement and limp mode on a 2.5 TDI

Hello,

"I'm experiencing a problem with my T5 van, which has a 2.5L AXD engine. When I accelerate gently, around 1800 RPM, there's a noticeable jerkiness. The cause seems to be that the turbocharger is building boost abruptly (which is quite audible)."
I also have the problem that it repeatedly goes into limp mode during longer journeys. The error code stored is "boost pressure exceeds limit."

My suspicion was that there was a leak somewhere in the exhaust system, as I could repeatedly hear noises, especially when towing. However, I haven't been able to find any leaks anywhere.
Die Ladeluftstrecke habe ich bereits mit Nebel auf Dichtigkeit geprüft, ebenso das Unterdrucksystem. Unter Druck kann ich die Ladeluftstrecke leider nicht prüfen, da mir die Mittel dazu fehlen. Ölige Stellen sind aber nirgends zu sehen. VTG is common.

So far, I've already replaced quite a few things.

N75
AGR
Boost pressure sensor.
tandem pump

Hi Andreas,

Please provide the text you would like me to translate from German to English. I will then give you only the translation, without any explanations.

Best regards, Rainer.