Power loss in AFN

Hi diesel experts,

'Despite having 136 horsepower, my car only reaches a top speed of 170 km/h. It also feels quite sluggish until 3000 rpm. I used to have a higher top speed of 210 km/h (in a Sharan!).' Through some tests, I've now discovered the following:
The VTG (vertical travel gauge) is off by approximately 5mm. Is that acceptable?
The LMM (likely mass airflow sensor) should be working correctly, in my opinion. However, there's a further drop in performance when it's disconnected. Am I understanding this correctly?
The cylinder head was replaced 15,000 km ago. I had the power loss even before that. The workshop checked the turbocharger, and they claim it's okay. Unfortunately, I don't have any electronic testing capabilities. Please give me some advice! Can I reliably test the LMM (likely referring to a Mass Air Flow sensor) with a multimeter?

Regards,
Markus.

Hi.

A VTG adjustment range of only 5 mm could already be a problem - normally it's about twice that.
Take a look at the error database and see what's been reported about issues like stuck VTG (vehicle train control) systems, etc.
It's also largely my own story of suffering, which (for now) ends with the larger container.

Regarding the LMM: if disconnecting something causes a performance loss, at least it's not completely broken. However, it is possible that he is only measuring slightly too little, which can already cause a "partial" loss of performance.