My 05expedition (5.4) has 175k on it, and we decided to trade it in, then it started running badly, has a miss, idles rough. Just put 2k miles on it in 4 days on a trip without any problems. Anyways, I have a po352,340,420 and 430. Buddy of mine said it could be the timing, and would be about $1000 to fix. Don't really have a thousand dollars to put in it just to trade it in, any help is appreciated!