Alright so I replaced the pump + filter, and the car started right up! After driving for a day, I got a Check Gas Cap light again and a P0445 code. I've replaced the EVAP canister, and the purge valve on the motor.. so I guess maybe I'll go with what I should of replaced initially but doubted replacing: the actual gas cap. If that doesn't fix it, I guess I'll re-check the canister and make sure it's tight.

Thanks for the help guys!