Not that I was doing it to show how awesome the car is, I was running some simple post-repair tests.
I had a badly fluctuating idle while in park, and while diagnosing the issue I managed to rip the stock rubber intake tube, so I replaced it with an aftermarket metal tube/cone style intake. Thus far, the idle seems pretty good, still fluctuating a bit now and then, but when lightly revving to 2.5k-3k RPMS while in park, it'll die if you just let the RPMS drop naturally. If you depress the decelerator gradually, it does not die.
While driving, everything runs just fine. What is this!? I can't find any vacuum leaks. I am pulling a purge valve code, and a MAF code. I cleaned the MAF today, too. Maybe it needs replaced?