Ok, bare details first then the more in depth explanation: Yamah 25hp 2 stroke autolube/presision blend, starts up fine, runs on muffs or in a barrell of water fine, will throttle up to high revs in neutral, under load on a boat however it has the same predictable issue - start to throttle up, reach the point just before planing and it loses all power, goes slower and slower the more throttle you give it, the more you open the throttle the worse it runs, vibrating and misfiring as soon as that point is reached. Tried cleaning the carbs, changed the plugs, checked electrical connections, different fuel tank and different fuel line and bulb, adjusted idle screws, timing linkage, changed the oil in the oil injection tank and made sure it was full of oil at all times before running, suspected a leaking reed valve in the bottom cylinder (2 cylinder engine) because of oil blowback in the bottom carb so I fitted a new reed valve assembly, nothing has made any difference, no matter what I do the motor runs the same afterwards every single time. I am at a standstill with this problem and any suggestions or help would be very welcome. One more thing for now, the warning light on the centre of the control panel has had its wires cut off and this is making me wonder if the problem starts here? Thanks for reading.