Looking for help. I have twin 225's with 350 hours. The boat is winterized each year. This season after two fishing trips or about 20 hours of operation, I had the water pumps and thermostats replaced. Since that service I have experienced a "rough idle" on the starboard engine when the rpm's are between 700 and 800. Above this range it cleans right up. WOT is around 5500. No other problems. I had the boat pulled by the dealer and could not find any problems. The service tech came out on the water with their laptop and computer cable connected to the motor. Everything checked out normal even while the rough idle was occurring. They checked the fuel pressure and found no problems. Fuel used since last season has been non ethanol. I have replaced the plugs. One last thing, initially the rough idle occurred once in a while after it warmed up. It seems do it all the time in that rpm range.