It turns out I had burned some plug wires on the turbo car, and it was causing a hesitation and misfire between 2 and 3k rpm. I tried a spare set I had laying around and it did the trick. AFR's are more steady at all RPM and the car runs smoother everywhere. The misfiring had been developing over the last few months, so it eventually got pretty annoying.
The funny part was after I parked the car and popped the hood, it sat for maybe two minutes before the spark plug rail melted like cheap plastic. If the other rail melted like that I guess I would have realized the problem sooner. You definitely need some heat shields in there though.
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