I have a 150hp 6 cylinder merc outboard I took it out once and ran ok but on way home after we changed over fuel tank at full throttle it wouldnt even get up on plane sounds like it was starving for fuel I had it serviced and carbs cleaned out and these were full of water but when I took it on water had same issue. When engine is out of water it revs as per normal and when you put it in gear it spits out water and revs as it should but the minute you lower the engine in water the revs die down and boat barely moves if I raise engine outof water it will rev up its like theres no power under load

