The other issue is when you chop the throttle from a high setting, to idle.  This is very strange.  Say the idle is set at 1900 rpm, and I’m running at high throttle.  When I chop the throttle, the rpm goes low, to around 1600 and stays there.  During this time, the MP is 16.0, and the engine is very rough.  It will stay here forever, but if you turn the mixture knob about 90 degrees CCW to lean it out, it smoothes out, the rpm increases to 1900, and the MP drops to 13.0.  If you are at a higher throttle setting, and decrease throttle more slowly, it will come down to 1900 rpm, 13 MP, and smooth.  It also seems like the engine is jumping back and forth between the dual map ranges, and I believe this false 16" MP reading at the rough, low idle is from the dual map.  I think I even proved that to myself by watching the EM-2 screen that shows EC-2 readings.   I’ve got some work to do on this one, but it's just a tuning issue.