I replaced the fuel pump on sunday and drained the tank. it had some dirt in it but there was no rust. I put clean gas in it and it ran great no missing or sputtering. about three hours later I left it idling for about 15 minutes. It started doing the same thing barely keeping itself running when you touch the gas but it still idles fine. I am putting a new fuel filter in tommorow and got a maf from a junk yard to go in tomorrow too. any suggestions?