Unusual pinging issue (2005 Ford three valve V10)

Old guy,
Yeah that's what I'm thinking. This is not a "trivial" problem and a mid-altitude new ping is not something to sneer at. Something bad is going on inside a cylinder of that engine and it won't get better. High octane fuel would be considered purely a diagnostic move. R&R spark plugs is a miserable job on this engine and I did not recommend the reading of spark plugs as a lark. I would make sure my Good Sam towing was up to date. Depends on the OP to learn the eventual fate of this issue...