n75 valve boost solenoid?

[Bellic]

anyone know the part number for the n75 valve for the 1.9tdi it is a passat but is the same as the audis , the dealer says theres two solenoids not sure the other one is and where is the n75 located?
the car suffers from intermittent power loss

 

[Aky]

What power losses are you having?

 

[Bellic]

car will not boost sometimes then sometimes it will , like the turbo no working?

 

[Prawn]

my mum had this problem, as did my friend in his A4 tdi, both times it turned out to be a MAF problem.

i thought the tdi's had a variable geometry turbo? and as such no wastegate? or is that total rubbish?