I have changed out the EGR, EVR, DPFE, all the associated vacuum hoses.

Intake Manifold => EVR vacuum hose,
EVR => EGR vacuum hose,
EGR Tube => DPFE hoses.

The only thing I haven't replaced is the EGR tube.

I get the following reading on the DPFE... from .7V @ 0% to 1.9V @ 90%. From what I have read, I should be getting closer to 5V @ 90%. Not sure why the readings from the Upstream and Downstream vary so little.

Does anyone have any ideas on what to look at next?

 

I have been told that clogged ports inside the throttle body will cause this issue and that cleaning the throttle body may solve the issue.