If you have access to a scan gauge, you can connect it to verify the boost levels and the MAP sensor operation. Conversely, you can also "T" a standard pressure gauge into the MAP sensor feed to measure boost.

Also, when the car is idling, remove the vacuum line on the waste gate and connect a vacuum gauge to it to verify there is 100% vacuum present. As a test, you can also connect the vacuum supply line going to the transducer directly to the waste gate so you get 100% boost all the time. If you regain your performance doing this, you can take a closer look at the transducer.

Rolf,

The transducers are variable vacuum devices controlled by a PCM signal from the ECU. If you can do with a "on/off" control rather than variable one, you might do well with an EGR purge or "switchover" valve.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250