Try cleaning your exhaust back pressure tube. You might have to also but a new sensor for the ebpv. The sensor is located right on top of the water pump behind the engine fan. It has a tube going from it to the right exhaust manifold. If the sensor goes out or the tube is clogged it can make the ebpv stick acting like an exhaust brake, thus not letting you get full boost and power. If that doesn't do it then maybe the valve itself is shot. Usually is just the sensor. Does it making a hissing sound out the exhaust pipe?