This is completely bizarre.
I went through tonight and cleaned all my grounds again. Wire brush on a drill, going through each connector and made sure they looked like a mirror. Blasted em with brake clean and wiped er down with a rag when I was done. I scanned for codes and got not only the two I originally had, but now a P1698 code to top it all off. I tested the same pins I did last time to see if it was a ground issue. Low and behold, pins 9, 21, and 22 all read about 200 ohms higher than before.
I tried redoing all my ground cleaning two more times to no avail. I might screw with it tomorrow evening. I just don't know what's going on here.