It looks like I may be wrong, I was basing this off my 6.0L knowledge, which that was the case. It was used for EGR by reducing manifold pressure under higher loads. TMK it was never used for any other purpose and should be wide open most of the time. All 6.4Ls may all come with throttle bodies from what I can tell. It's mounted to your intake manifold and where your cold-side boot clamps too.

If oil was sitting in the inlet, more than likely I suppose, but end-play is usually your best tell-tale of a failed bearing.