Intermittent boost loss

[Waterloo]

If it is whining or whistling, there may be a loose clamp somewhere. Have you inspected the clamps on the actual turbo itself? And the the exhaust back pressure sensor, has that been replaced? I believe it is located on the top of the motor where the coolant thermostat is located. Tucked in behind there, like a 27 mm socket to remove if memory serves me right. I have a CM-871, so that sensor may have moved on your motor, but I think it is still there in roughly that location.

And that turbo, is it slobbering oil? And how about the actuator? New or old? And when the actuator was installed, was it calibrated with Insite?