My son went to mow and when he filled the gas tank he left the cap off. Since we have a lot of dust it apparently sucked some in. I started by replacing the fuel filter but it keeps happening. Every time I change the fuel filter I drain out the gas in the line until dirt quits showing up. Then o go mow for awhile and everything is fine about an hour or so it starts to bog down and die. I repeat the process. I am looking for a better solution, more permanent. Anybody got any ideas?