Pulled injectors from cylinders 1 & 3 today after determining the miss wasn't coilpacks. Been running e85 for about 3,000-4,000 miles with the injectors in for about 50k before that. Orings were nasty, injectors benefitted from being sprayed with MAF cleaner, but they definitely didn't have any kind of gunk build up on 'em.
Swapped injectors, missfire gone. Go figure, but I'm psyched.