Deb
You can pour some bleach in the dishwasher and run it through a cycle. Always use bleach by itself, never mix with any other types of cleaners.
I am beginning to question if what you have is a plumbing related odor. What exactly did the plumbers say about the odor? Did they believe that it was sewer gas (although I don't know how much trust I would put in plumbers that did not notice the non-loop in the dw drain line and deal with it)? Did they check to make sure trap was maintaining its water seal? Was any kind of test done on the vent to be sure that there is not a break there? Even though the dishwasher hose is not looped, this should not be causing the horrible smells you are describing, especially from all new piping, disposer, dw. The major reason for the loop/air gap rule is so that if the sink backs up, the backup will not run through the dishwasher hose and into the dishwasher.
You have basically replaced everything that comes in contact with the drainage system from the fixtures to the wall. So, I would be maybe looking for another source for the smell--a small dead animal(s) rotting in the toe kick or wall, mold, mildew, etc. Odors can be tough to identify, but it is necessary, since the remedy is dependant on the cause.
Deb
The Pipewench