Owned since 2005. Has app. 500 hours Well meticulously maintained. Never ANY PROBLEMS. New FUEL AND AIR FILTERS. Mowed 2 acres 2 weeks ago NO PROBLEM. Now while mowing at wot after about 15 minutes mower will immediately die like I turned the key off UNTIL I PULL THE CHOKE ON, It spits and sputters for a second then takes off for app. 1 minute then same thing all over again continuously. After about 5 minutes of this I QUIT. I then pulled the carb. bowl off and it was spotless inside. Test drove and same thing all over again. Poss. FUEL FILTER? OTHER IDEAS?