Another update.

I finished replacing my alternator today and also replaced the wire from the 2nd terminal to the x4/10 junction box. Now I've got full voltage the way I should.

How does this relate to my idle issue? Well, I don't have an idle issue anymore. The idle is completely stable now. Also, no stalling. No stalling at all. Hot or Cold.

Before after a good drive it would almost always stall at a red light or stop sign.

So here is my theory:

1) The alternator has been going bad for awhile and throwing voltage spikes. These abnormal voltages were causing all the odd behavior.

or

2) The alternator had nothing to do with it. The change in idle behavior/stalling is only because it's summer now, and the problem is actually a bad temperature sensor.

Not sure which one is correct. I'll just keep driving and see if the issue comes back in the winter.

Any thoughts? Has anyone else had an idle/stall issue that was traced back to either a bad alternator/voltage regulator or to the temperature sensor?