check the lines anyway, omc as has what they say is ethanol acceptable lines since 90 and they still can cause trouble.
my guess is someone is due for carb servicing, pull em and clean them out, also check carb bowls for leakage if they canleak any amount of fuel they can suck air.
post some pics if you can
seafoam is a great cleaner and additive but 11 years and a million hours you may be getting diry, prevantitive nain, is easier to keep it clean than to fix it once it's acting upthan