[Suzie]

Update: I located Mike Sabarese at Tustin Hummer (Calif). After just a few moments to talking with him, he said the problem is likely the same thing my trusted local mechanic said--a bad PCM module. He reiterated that it could not be the key ignition switch.

I am removing my vehicle from Cerritos Hummer today and taking it to Tustin to be repaired. As the dealers charge a minimum hour's labor for each item they check out whether you have them repair anything or not, I was told my charge would be around $200. That minimum charge gets applied to any work they do.

As they already replaced the ignition switch, despite my repeatedly, strongly telling them it was most likely not the problem, and the charge for that was $220, I told them to just leave it in. Might as well get something for my money. Told them I want the switch they took out, as nothing was wrong with it. Said I could use it if the new switch goes bad (ha, ha, ha).

The service writer called back and said the final charge would be $265. They are adding on one half hour of checking out the throttle body. Whatever. I am just glad to be getting it out of there for under a grand.
They still think the throttle body module is bad.

So now it will be off to the Tustin dealership, where I have faith that Mike S. will solve the true problem. I will update so stay tuned, especially if you having the same kind of intermittent problems/battery drains/reduced engine power message. 2003 Hummer H2. Oh, and THANKS for all the help and suggestions!