They also pointed out that the rear differential had gone from a drip to a leak--and yes, the floor of the garage was already telling me that this situation was getting more serious. This turned the $100+ rear differential service into a $500 repair.) They also recommended replacing the fill plug, which I already knew was damaged. (It appears that it is a 10mm hex socket plug, and some grease monkey somewhere apparently used a 3/8" hex socket, which removed it, but over time has slowly turned into something closer to a circle than a hexagon.)
I am quite sure that all of the recommended changes are completely necessary. It's still quite expensive. It makes me wish that I was still earning private sector wages, so this wouldn't hurt so much. The only good news is that the semester has started, and I now have 1 3/4 full-time wages because of it (or about 3/4 of a full-time private sector job.)
UPDATE: I suspect that it was mostly replacing the fuel filter, but the Corvette is now really, really quick again. It was still pretty fast before, but it is again back in the, "When will I ever have occasion to get my foot all the way to the floor?" mode.