I might have more after I digest all that you wrote, but the plastic thing by the fuel filter is your rollover valve. As long as its upright, air should go both ways, but if you roll the car it'll keep fuel from spilling out.

Your gas cap is relatively new/good condition right? If so, it seems that everything in front of the filler pipe is working. So (AFAIK) that leaves the fuel tank pressure sensor, the filler pipe, or a blockage in the pressure sensor pipe. None of those are fun to replace. If you can't smell vapors when/right after you fill its probably not the filler pipe. You might try over-filling to see if it'll leak out the pipe.

Fuel tank pressure sensor requires you to drop the tank, not fun. At least until the code comes on for real, not just pending, before you undertake that amount of work. And you should probably confirm no leaks with a smoke test before you drop it too..
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If you're not driving it "like its stolen," are you really driving?