dont you just love those lights? ive seen them too many times but its useually cause i broke something trying to do things i read in here lol! so for me the common problem was the gas cap it took a couple days for it to shut off by itself, the MAF, i broke it trying to clean it, one time it pulled up my idle control valve was bad, i poored some injector cleaner in the gas tank and some how it shut off almost immidetly, um ive heard a bad Cat can set those lights off, other than that thats all ive had experience with. Ive been check engine light clean fir 3 snd a half weeks, im never touching anything electrical again