Great feedback...
My original strategy was much better in shifting performance, a light touch on the throttle would instantly and seamlessly put it in a lower gear, much how our Audi and BMW's I've owned in the past shifted. It was, in fact, one of the things I liked best about the truck when I bought it.
Along with an unrelated TSB, Ford flashed a PCM update and the shifting strategy has never been as good. Around town, kick-downs aren't nearly as seemless and you really have to give it plenty of throttle... What typically happens is no kickdown, boost builds, RPM's rise, THEN it kicks down anyway with a huge rush of power. Not smooth or natural.
For this particular problem, it usually occurs when i'm driving at highway speeds, 55-70, typically mountain driving conditions. I want a little more power, not gobs of it. I'd be happy to have it downshift a single gear quickly and spool up a bit, but it won't do that... I either feather the throttle and potentially get flutter or womp the throttle a good bit and I'm gone.
I've heard some suggestions that bad or weak HPFP's can cause a bunch of bizarre symptoms, but again, I wouldn't think it would happen in only in a lower rpm (lugging?) situation.
Even the custom tuners don't want to (or can't) put the 'breath on it to downshift' characteristics back in my truck.... Moral of the story: If your truck or car is running well, do everything possible to prevent the dealer from 'upgrading' it!!!