Tangled Up In Blue (Think I found my bog problem)

I finally caught my "bog on throttle flipping" in the act.

Logger reveals that what's going on is, a spark pull
to 7 degrees advance. This "hangs" the engine & trans
in a cut-power state it seemingly can't get out of. Only
by backing of WOT does it release. Like, with 7 degrees
advance it is basically rev limiting itself and won't climb
higher than about 4500RPM, and there it sits.

It appears that the mechanism is, when I lift my foot it
upshifts and when I put my foot back down the flash
(PCM model of it?) of the converter makes my torque
management activate; for some reason the shift cycle
appears not to complete, like there is some "hole"
it can't crawl out of at that reduced power, a positive
feedback of some sort?

I went and greatly reduced the TM spark retard vs
% torque reduction table (pulling 10 degrees max)
and it seems like maybe it's gone (though it's been
surprising me at intervals).

What I don't understand is, since TM is supposed to
let go once the shift is complete, why does it persist
like that?