1.9 TDI (AWX) Audi A4 runs roughly when idling.

Hello everyone,

I've been having problems with my 1.9 TDI 96kW engine (AWX) for the past three weeks. It's running intermittently.
When idling, the engine runs unevenly, as if the fuel injection amount is too low. The idle speed control also seems plausible. All other values are also OK. The compression is also within the optimal range. Air filters and fuel filters have been replaced.
No performance loss, no blue smoke or soot.
The oil consumption is approximately 1/4 liter per 5000 km.
What surprises me... the idle consumption has decreased from 0.6 l/h to 0.3 l/h.
The overall consumption has also decreased from 5.8 to 4.7 l/100km at the moment.

I hope someone can help me out!!

Greetings to everyone