I think 87GNALKY was exactly right when he pointed me to the temperature of the wideband sensor as the "what's different" between the first start of the day and subsequent starts (and key only starts) . I decided to take the GN to Church today and initially planned to disconnect the wideband 12V and see if on the return trip, the boost gauge initialized properly. Previously it took at least 10 hours to "reset". But when I went out into the nippy air of a fall morning I had another thought. Maybe in the cooler temperatures the sensor would cool quicker and just maybe two hours would be enough even with the wideband connected. So always looking to experiment without disconnecting or moving anything I gave it a try. Sure enough, after only two hours, the boost gauge initialized perfectly. This has NEVER happened before all summer. This also squares with the fact that the problem did not originate until the warm weather arrived in May. And so I think the path is clear. The wideband circuit has to be isolated. If only I had the skill to do it. Just like some people are "singing impaired" my weak spot is wiring. I will have to have my shop do it if I want to be sure it's done right.Yes do that first and if that doesn't work separate the boost gauge .
A man has to know his limitations .
Thanks again to all of you. It took the collective thoughts of so many people to bring me to the solution. Couldn't have done it without you all.