I have a yamaha f250 as stated above. I have owned the motor for two years now and it has been great. Recently while offshore the motor just above idle in gear started to sputter and miss. after about one minute and a little more throttle it cleared up for the the rest of the day. After this i changed the spark plugs and the fuel filter on the front of the motor and the water fuel separating filter under the console. I thought maybe the fuel let some water get through and that was the problem. The next two trips offshore the motor ran great as usual with out any signs of the strange idle until the last trip out. During trolling at about 7mph it ran great but two times the motor was brought down to the slowest speed to boat fish and it started to act like it wanted to stall. While it was doing it i placed it into nuetral and it idled fine again until it was put back in gear at the low speed. After this it again ran strong all day I need help.