Well, we finally gave up and the Dealer agreed this Nitro was a lost cause.
They will retain it as a Demo for awhile to see if any of the repairs result in reliable resolutions.
Meanwhile, we have "traded up" (so to speak) for a 2006 Jeep Commander, which would have been our first choice but was a little too pricey at some $9K above the 2007 Nitro.
With 0% financing at 60 and even 72 months, the total cost of ownership for the 2006 Commander was now only about $1K over the cost for the 2007 Nitro. Realizing that Commanders have had their problems as well, we're simply hoping for the best.
To all you Nitro owners: good luck and safe driving. It is definitely a fine-looking, fun-to-drive SUV and we would have enjoyed ours if it had been reasonably dependable.
Now, I'm off to the Jeep Commander Forum!