Your turbo waste gate is controlled with the solenoid with the use of vaccum.The vaccum pump supplies the vaccum and the solenoid controls the amount of vaccum.This solenoid is actually controlled by the ECM,but the solenoid is the tool of the ECM to control the watsegate.Your wastegate must have vaccum to it to close.Without vaccum,the waste gate stays open and you end up with a lack of power.I hope this will help you fix the problem.
Chuck's