Thanks Brian for the link to the service manual. It does not explain my issue exactly but there is a ton of info that will certainly come in handy.
Took the air filter out several times to clean it. Being from the 2 stroke world I am more than sensitive to air flow issues. After the 24" powder explosion I actually took the air filter out and dunked it in the Whitehorse hotspring. One day we encountered a long stretch of deep rutted double track with 4-5 foot high sage brush. It took the front 6-8 inches of the radiator scoop off each side. That night I checked the filter. The Twin Air filter was good, but the screen behind it had a significant amount of sage and needles on it. I assume things might have migrated beyond that but the bike has been running great.