Folks, <br /><br />I've been lurking here for a while and have to say this forum is very helpful. I've run some searches, but can't seem to come up with my exact problem, so here goes:<br /><br />I have a 40hp Mercury outboard, 4 cylinder, 2 carbs, 2 stroke, model ME40-ELPTO.<br /><br />Motor will run all day on the hose, or on the water at less than 2/3 throttle. At around 2/3 throttle, the engine surges badly. Above 2/3 throttle, the engine runs fast and smooth, but shortly dies like someone just shut it off.<br /><br />When the engine dies, restarting is difficult. I pulled a plug right after the engine died, and it was dark and very tacky/sticky and dry. Usually the plugs are wet and oily. That confused me because i swear i could smell fuel as i was cranking.<br /><br />Also, the primer bulb was a bit soft, but not collapsed when this happened. I ran the motor for about 20 miles today at 1/2 throttle, and it runs smooth, but go full throttle and you have about 5 mins till a quick stall.<br /><br />Also, the idle could be better, it seems a bit rough and weak. It seems to start fairly well, but starts easier warm when the idle speed is set high and a tap of choke is given.<br /><br />So far, here's what's been done:<br /><br />Cleaned old plugs<br />Decarbonized motor (I followed directions on ValvTect can, and piston tops have carbon, but no visible carbon on the pavement after decarbing, what did i do wrong?)<br />Installed fresh plugs<br />Old oil looked like death, so dumped it<br />Filled oil reservoir with Penzoil Synth TCW3<br />Added some decarb (looks like old ATF to me) and stabilizer to fresh gas<br />Ran it for 3 hours on the water <br /><br />This motor/boat have sat around quite a bit, and i've kind of inherited them for the time being. I live on a canal, and have a 15 min idle/no-wake before i can get-to/come-back-from to the gulf.<br /><br />Last thing, if you could get a manual for this motor, which one is best? I am a fair shade-tree diesel mechanic, but this 2-stroke/carb/spark stuff has me a bit hesitant to dig in.<br /><br />Thanks in advance...