Same symptoms on both tanks. It doesn't act up as in come and go, its just gutless with very low boost output (of course if my gauge is reading accurate).
I disconnected the linkage arm from the butterfly, there was a stiff spot in the rotation of the butterfly but just a small hicup. I could not move the rod when it was connected to the actuator with the motor unplugged and truck off, I could move it once disconnected from the accuator.
I wired it open (atleast I assume open) and felt no change. I had a coworker fire it up and I moved the butterfly and this was where it was at when the bracket was against the stop on the housing, when pushed the other way to lock I could here the back pressure build in the turbo.
It has the oe fuel pump in the motor valley (252K on it). I had the fuel bowl out last year and replaced leaking rubber lines and the bowl heater. The ICP sensor was replaced last summer with a motorcraft as well. Both valve cover gaskets/harness's were also replaced last summer.