Just a quick update: Ran over this morning to Harbor Freight to pick up a manual oil pressure kit. I have not installed it yet. On the way home I drove on the highway again at 70mph to see if I could reproduce the low oil pressure problem when I came to a stop light. It would seem that the oil change made a difference. No check engine gauge light and the oil pressure stayed rock solid the entire time. Obviously I am going to drive it some more and see if the problem is really gone.
One question I have: Can I get a "T" fitting to put on the engine block so I can monitor the manual oil pressure gauge I just bought at Harbor Freight as well as the "dummy" gauge on the dash? This way, if the check gauge light does come on, I can see the actual oil pressure on the manual gauge.