You’ve got a lot of possibilities there is the problem. Refueling vapor control valve, fuel tank temp sensor, evap control pressure sensor, evap canister vent control valve, evap canister purge volume control valve, and all the hoses, including the fuel filler tube, connecting them together.
You’ve already replace the fuel filler cap, right? hmm … well, there’s a couple of bulletins on the 1.8 L engine I see for the evap system, 08-023A ECM update, 03-041B engine controls. Google those numbers, maybe you’ll find something of interest.
You said you replaced the filler cap, and that seemed to help? It’s possible the replacement isn’t fully working either. Beyond that, if I had this problem I’d take it to a shop and ask them to do a smoke test. There’s so many possibilities of where the leak could be, that’s the problem of the parts-replacement technique. If you want to try parts replacement anyway … hmmm … evap canister vent control valve or evap canister purge volume control seem the most likely.