Engine ran very well from idle up to about 2400 rpm. Beyond 2400 rpm it felt like it was going to stall, but with surges of increasing speed. Additional information – using all new non-ethanol gas, the fuel filter is about one year old (but not really used) - first time the boat has been used in about a year. The engine ran great at 2400 or less for the entire day. It’s a 2001 Yamaha 225 four stroke. Any ideas on what to check are appreciated.