Boat ran awesome for since 2010 "purchase with 50 hours on it", to mercury high 5 stainless prop 19 pitch and it could really get of the hole (time to plane was about 3 seconds). This year, out of the blue, on full plane and about 4000 rpm, it suddenly started to decrease all the way done to 800-2500 rpm at full throttle and I had to constantly work the throttle to keep moving. By the time we got to shore it sucking air like a vacuum from the top of the engine. I then changed out the rotor, cap, and spark plugs, but that made no difference. When my mechanic went to change out the fuel/water filter it was less than hand tight. The fuel had about 2% water in the filter. Changed the filter and suction sound went away. He hooked the computer to the engine and we went up and down the lake a few times. I told him it was sluggish and only 4400 RPM at full throttle. It was know taking about 10-15 seconds to get on plane! He said that the computer was not shown any faults or errors and after examining the parameters for awhile, said the boat was running fine. Why is it that it can no longer reach the full spec RPM of 5000 RPM and took so long to get out of the hole and seemed so gutless. It also backfires in quick successions only when getting out the hole.
