I'm showing a MAP of around 55kPa, about half of sea level static, with an idle of 1400 and an AFR of 18:1.

I'd like to drop the idle further.  I had it closer to 900 before, but the idle is now rather rough, which I'm attributing to the ultra lean mixture.  Is this the lowest MAP I can reasonably expect?  Or is there a reasonable expectation of a manifold leak?

BTW, Lynn,  now that I have a fairly stable idle, I'm looking closer at the timing.  It looks as if the RPM jumps from 1450 to 1250 as the timing drops from 21 to 20.  There are many places in the graph where I can watch the RPM following the ADV up and down, which tells me that I still have a lot of power left hiding in the timing tables. (The RPM rises when the timing does.)

I also made a point of noting the EGT gauge reading.  I stayed down around 1200*, for the most part, but did have an excursion up to 1600* with the throttle 70% open.  The MAP read 93kPa. The AFR was swinging between 15 and 14.5.   I've since shifted the numbers to avoid doing that, but it will have to wait to get tested.  Had surgery to repair a torn meniscus on my knee today.