A3 8P 2.0 TDI: Engine Misfire at Idle

Hello, diesel engine specialists,

I own an Audi A3 8P, manufactured in 2005, with a 2.0 TDI engine.
The car is just causing problems; it's got a mileage of 195,000 km.

When idling, but only when the engine is warm, the car vibrates, although not always; sometimes it does, but often it doesn't. It's as if the car is misfiring. The RPM gauge remains constant in this situation.

The two-mass flywheel has been replaced, including the clutch.
PD elements, inspected and cleaned.
Throttle valve cleaned.
Error memory is empty!

We're stuck, and neither I nor our workshop know what to do. Please help, and any advice would be useful.

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