Thanks.
I just got a P0455 code and one of the things it said to check was the evap canister. I checked everything around the fuel tank and everything looked fine. As for the fuel cap, I replaced it two weeks ago because I got a P0455 code then, too. I replaced the fuel cap the check engine light turned off. Now I've got it again. The guy I spoke to at Auto zone said I can exchange the one I bought for another one but I thought I'd check the evap canister before I did that.
I'm open to other suggestions.