wastegate solenoid performance fault. you might just be running spring pressure.
it is located on top of the intake manifold, has one vacuum line in and one out plus it's connector. kind of towards the middle rear. the out vacuum lines Y's just past the throttle body.
i'm not answering you on what is wrong. i'm explaining the fault and where it's related component is.
your possibilities are the solenoid, the vacuum lines to and from, the wiring, or something completely outside of that box of things.