The CEL came back on, so I plugged my scan tool in and pulled the codes. Looks like I'm dealing with two separate issues-
Issue one- P0441, P0446, P0455. All evaporative emissions codes. I checked the gas cap first because duh, and it is broken. So I'm gonna get a new cap for it and go from there.
Issue two- P0171 and P0420. Lean code and catalyst efficient code. The catalytic converter is less than a year old, so it would surprise me if that was the issue. It was an aftermarket one, but I've never seen one go bad that fast (that wasn't bad straight out of the box). Fouled O2 sensor is a possibility due to the oil burning. The downstream is original. The upstream isn't very old.
I've got some diagnostics to do before I start throwing any money at it. There was also an airbag code, B1660, no airbag light though. I'm not too worried about the airbag code, I'm gonna pursue the engine codes first.