So, in the end, it was not a bad fuel injector, it was a loose connector because the dang dealer mechanic did not fully seat it when they worked on it six weeks ago. (It has to be them, because the fuel injector connectors were never touched other than that one time.)

I really, really hate having other people touch my car. Especially dealer mechanics that are under time pressures and paid on commission.

Doctor Volvo charged $85, which was probably one hour. Considering the level of support, loaner car, and other things they checked while they were at it, I think the price was very fair.