OK, I finally got around to doing something more drastic to solve this issue. The verdict: FINALLY FIXED! (should be....for now at least)
I didn't want to delete the box, but I did remove it, and dumped all the charcoal out. It sounded like there was a separate chamber that still had some in it, but, I shook the box for about 10 minutes and about a half gallon container's worth of charcoal slowly poured out until there was no more coming out.
I then cleared the clogged vent hose. The clog is probably 4 inches away from where the vent hose connects to the charcoal box...you can feel it if you squeeze the hose with your hand. Just knock it against something and it will clear itself out.
I reconnected everything, no CEL, went to the gas station and pumped at max flow and the pump didn't stop a single time. Put $10 quickly, like normal.
I'll update this a couple weeks from now in case any problems arise.