Problem solved thanks to everyone here - and Jim at Lakeland.
"isolation diode open" per the rectifier test
http://www.kawatriple.com/cdih2/cditesth2.htmI purchased/installed one of Jim's "all in one" CDI boxes. Ran it 40 miles yesterday and 30 miles today and the bike runs better than ever. The slow degradation of these old ignition systems is tricky to isolate because the symptoms crossover many possibilities.
Now:
1) The engine returns to a stable idle quickly (no rev hang)
2) Emissions from all three pipes smells and looks even.
3) The power band changed - the midrange is much stronger and the top end screams!!!
4) Definitely more complete combustion (downside - no more smoking out those angry Prius drivers)
5) Engine never seems "lazy" (think heat soak on a turbo engine)
Basically it runs like three really pissed off chain saw engines tied together.
A word about Jim at Lakeland. He is the "real deal" on many levels.
The build quality if his products is top notch.
Ja Moo is right - these old boxes are failing.
Nothing worse than slow degradation with intermittent failure.
The bike is reliable again - - - - - - and smells so gooood!!!