Hello guys and thank you for the awesome info. I've been reading this thread via Google Translate and I wanted to add my story should it be of any use.
I have 2020 Stelvio JTD 209hp with AdBlue. I've had it since new and here the importer always filled up the oil to the max for the first 3 services. Now they have reduced the amount which they fill in. I have had plenty of oil in the intake, and I suspect that the oil segregation part has not been changed but definately has been over filled in the past. I will get the oil segregation part replaced in about one year when I have the 120tkm maintenance.
For the issue; I had P0100 code and started to lose power. Just like described in the original post, every time you ease off the gas the engine goes to limp mode. Restart and you have full power again. P0100 is actually a drift in MAF sensor value compared to MAP sensor value. Both sensors still show valid values but they just don't match. P0100 code links to MAF sensor but in reality, my issue was MAP sensor. I didn't replace any parts, just cleaned MAP from all the gunk (with MAF cleaner spray), gave it two days of driving and all errors went away. I believe if you replace the MAF sensor you also need to reset the values in the ECU to relearn the lambda values.
This is MAP before cleaning, I am amazed that it still showed values and no error code.
After cleaning I had errors P0100, P225C (Nox 1), P0101 (I disconnected the MAF sensor with the battery connected) and P2299 (brake and accelerator pressed simultaneously, no idea why). But given a couple of days after cleaning they went away.
This is the fault in Multiecuscan, when easing off (coming to a ramp on a highway). MAF value goes up, but MAP does not -> Error. Vertical line is where to engine goes to limp mode.
Attached is also the recording from Multiecuscan if someone needs to compare their values. This is
before cleaning!
Thank you all for the amazing info!