Believe me I wish it was as simple as kids messing around.
I think I figured it out!
Yesterday I saw my speedo was out 3%, and I KNOW I had programmed in 37's in the Trinity so I programmed 38" to see if that would manifest a change. It did NOT. I knew something was wrong after that and within a few blocks of driving off after that I realized I had NO speedo any longer and therefore nearly no power steering.
I tried reinstalling the 87 tune to no effect. Next I called Diablo support - "have you tried disconnecting the battery for 2 minutes?".
Damn, hadn't thought of that. Tried it and it worked like a charm.
Diablo support also said something to the effect that the re-calibrated tire size was in a module that would be reset by disconnecting the battery. Re-installing the tune wouldn't help. And went on to say that if I experience odd problems like this after installing a tune I should again disconnect the battery.
By doing so, my speedo came back online .. steering became nimble again, and low and behold my alarm has NOT acted up again since!
Done ... ghost in the machine 0, Var 1