I have a mercury 40 horse 1991, 4 cyl, 2 carbs, oil injected. i bought this with a bass tracker 3 weeks ago, its been sitting for 3 years and he never drained or winterized anything. it started right up and runs great with the water mufflers on it in my driveway, took it out on the water and it just puttered like a dead dog, with full throttle it was even worse off. gas was shooting out of the top carb ,i checked the gas lines they were all fine but one had black tar substance so i replaced it. sprayed some decarb cleanerfrom the boat store it caused one hell of a smoke screen by my house, but help out a little, i took it out yesterday, ran a little better but only like a 10hp. i have no clue what else to check, motor sounds great out of the water but once under a load it does not want to get up and go, please help if you can.