ALH Engine: Performance Issues Above 3000 RPM

Hello TDI experts,

I have a Golf IV with an ALH engine.

Power: 66 kW.
Mileage: 125,000 km.
Stock chip, and no performance enhancements.

Seit einiger Zeit habe ich das Problem, dass im 5. Full throttle.
'The usual acceleration is absent. It takes considerable effort to reach a top speed of 175 km/h. It feels like you constantly have to ease off the accelerator and then immediately press it down again. This problem has existed for several thousand kilometers, and it doesn't seem to have gotten worse. If you rarely drive on fast highways, you might not even notice the issue.'

I performed a diagnostic test using VAGCOM and recorded the following values.

Turbo Charger Turbo Charger Duty cycle
Specified pressure. Wastegate bypass?
mbar mbar %
1132 1142 43.4
1040 1428 41.4
1948 2234 71.3
1948 2224 77.3
1948 1693 60.2
1948 1663 56.6
1948 1836 62.6
1948 1979 66.1
1948 2009 70.1
1948 1979 70.5
1948 1948 71.3
1948 1928 70.9
1948 1907 70.1
1948: 1795, 63.4
1071 1601 54.6
1948 2285 74.5
1948 1836 66.1
1948 1622 55.8
1948 1724 57.4
1948 1897 61
1948 1958 62.2
1948 1928 66.9
1948 1918 66.1
1948 1928 65.3
1948 1928 65.3
1948 1948 65.7
1948 1948 65.7
1948 1958 66.5
1948 1969 68.1
1948 1979 69.3
1948 1958 70.1
1948 1918 68.5
1948 1816 62.6
1948 1836 58.6
1948 2009 63.4
1948 2060 68.9
1948 1989 70.1
1948 1938 69.3
1948 1907 67.3
1948 1826 61.4
1948 1856 58.6
1948 1999 62.6
1948 2060 68.1
1948 1999 71.3
1948 2050 70.1
1948 1969 70.5
1948 1836 64.5

I can only conclude that I have a highly fluctuating boost pressure. I have already checked various things:

- VTG adjustment is common.
- The vacuum connections appear to be sealed.

Thank you in advance for your support.

Best regards,