(Dauphin Island, AL USA)
Engine has approx 140 hours, it had full 100 hour service at about 80 hours. When it runs for an hour, it develops a miss. At wide open throttle it (mostly) runs clean. But when I back down to about 4800 rpm, it starts to sputter. Its about every 5-10 seconds, it will miss and drop to about 4400 rpm. When I go to an idle, it will vibrate and miss.. Its done a version of this since new. They couldn't find a problem when in for service. It seems to be an issue after it warms up and is run for an hour.
All I know to try is changing the fuel filter. It site for 3 months max during the off season. I only use non-ethanol fuel.
Anything I can check, or advice, would be greatly appreciated.
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