In fact, I just realized why I run so rough on desent.  The MAP is probably getting pulled down below 10" and the pressure probably drops even more making it very lean...  hmmm  :-)

I mentioned this to Tracy one day, and he said (best I understood it) that the engine basically isn't running under these conditions.  For one thing, the injector duty cycle is so low that they effectively aren't opening.  I've noticed times in the pattern when I was descending at idle, and the engine noise seemed to almost go away.  Opening the throttle some made it start, then going to idle stop.  I got the distinct feeling that the engine was not running at idle, just like a car cuts the fuel on deceleration.  Interesting. 

Rusty (Maaaaaaaayby running Rev-3 by Sunday)