Turns out the thermostat was stuck open. Sadly, it took me about 5 hours to replace. Intrepid thermostats are located on the side of the engine next to the oil filter. You can either remove the alternator, some belts, and some metal to get access from above, or you can jack the car up, brave the tiny space below, and dedicate yourself to an oil change too. Naturally, they staked that thing in there too.
I learned my lesson working on this thing in winter and was smarter with the battery replacement. Tires Plus agreed to install it for free in addition to honoring their battery sale price. It took this poor soul an hour. On the plus side, my OEM battery lasted a decade. I can’t really complain…
