i noticed my engine hesitating. it happened after using the ramp on the interstate. got back on the throttle and it took a while to get fuel and get moving. next ramp.... happened again. tank probably had 3 gallons available. fueled up, got home, changed filters. next time the tank got low it happened again. today i drained the tank [2 &1/2 gallons] and pulled out the screen thinking blockage, but it was clean. any ideas?