Wastegate issues...i think

[cre]

Error codes?

If it's mostly stock and you're not planning on going beyond 10 to 12psi I'd locate a Bosch BOV... I can't remember the model # but it's been posted here a few times so you should be able to find it by searching.

Yes, a wastegate actuator with a shot spring would do it, but that's very uncommon. Typically the rubber diaphragm goes long before the spring will. Seized wastegates can often be repaired or you could get it welded shut and add an external wastegate. Personally, I'd try to free it back up and if that fails then I'd get the whole thing rebuilt and upgraded. Hook a bicycle pump to the actuator; Disconnect the actuator's linkage from the wastegate's arm; and pump a couple times, the arm should move 1/2" to 1" (You may try testing the BOV the same way). Don't exceed 15psi or so.

A wastegate that's stuck open really shouldn't cause any diagnostic codes to be set as far as I can reason... On the 7M-GTE the ECU judges boost pressure based on air flow readings, it doesn't see any reference to manifold pressure so it's most likely to just assume that the airflow is low at your given RPM because you're driving at a low load and thus not boosting (ie: driving down hill).