406 sri turbo intermittent boost

[martyb2]

my 406 turbo will sometimes boost and car goes like stink, but most of the time its as if the turbo wastegate is open (its not), are there any vacuum solenoids i should be checking, engine management light is not on, but sometimes will come on and then go off again, but not making a difference to how car runs... its a 1998 model 2.0 8v....cheers

[toh]

do you have any picture?