I've been going through this forum a lot today and it turns out this (posted under a variety of different names) is pretty common. When I had this problem I found out that it could just be because gas got into the evap system (instead of just fumes). I let mine go and would reset the "check engine light" every time it went on. (
www.scangauge.com is a good toy/tool that'll reset codes) To much gas in the tank was the cause I found in my research. So I stopped topping off at the pump and after a while the system got better.