No power with the TDI! LMM=OK!

Hello, I'm desperate.
I've tried everything now: I've replaced the LMM (lambda sensor), renewed all the filters, and possibly removed the tuning chip. But my Passat, manufactured in 1999 with 100,000 km (approximately 62,000 miles) and a 66 kW engine, still isn't running properly.
In the lower RPM range, the acceleration is almost normal, but above approximately 70 km/h, the power drops off, and the top speed is 140 km/h.
The diagnostic device indicates a faulty mass airflow sensor (MAF sensor) that 'freezes' at a certain airflow rate. We tried 3 different LLMs, but the error persisted!
I don't know what to do anymore! Who can help me?
You can email me at [email protected] or reply here. Thank you in advance!

Hello,

Have you measured the boost pressure yet? Fuel supply to the ESP is okay?

Best regards, Rainer.

ron30 wrote:

The diagnostic device indicates a faulty mass airflow sensor (MAF sensor) that "freezes" at a certain airflow rate. We have tried 3 different LLMs, but the error remained!

Hi.

Also, check this out:
Okay, I'm ready. Please provide the German text you want me to translate.

. . . it doesn't always have to be the LMM. . .