Low voltage at ECU is one I never would have thought of. But the problem did
begin with the onset of cold weather last week, which could lead in the
direction of the battery starting to fail. It's always on the yellow light
these days after letting the car sit for 20 minutes or so, indicating that
for whatever reason it isn't holding a charge so well. OTOH it cranks like a
 monster, fast and for a long long time. That's one test I've run, many times.

Sounds like the connection at the starter is a place to visit anyway, even
if it doesn't fix the problem.

It can't be too hard to check the voltage at the ECU when cranking. Any idea
what a minimum acceptable voltage would be?

But wait, if it cranks that well, how low could the voltage at the starter
really be?

Battery voltage could also explain why the starting has been progressively
worse.

Hmm. Stuff to try. Thinking out loud here. Thanks again guys.