About a week ago I started to experience intermittent rough idling for 20-30 seconds then it would go back to normal. After a couple days of this I got a Check Engine Light and then it started dying when I would be coming to a stop. It won't die when it has just been cold started, but once it has warmed up it will die almost every time I come to a stop. I can keep it running by putting it in neutral and keeping the engine revved a little while I am stopped. I read the code and it came up P0171. I've checked and I can't find any obviously damaged vacuum hoses. I even looked underneath and found what I believe is the hose to the PCV Valve and that seems to be in fine shape. At this point I'm thinking I'll probably have to get it into a shop, but I wanted to ask if there is any more easy things to check beforehand.