Hello<br /><br />I have a 1981 Mercury 25 h.p. It has low hours on it and it has not been beaten hard!!<br /><br />The engine worked very well since the two last time we've used it. It stated harder then usual, iddled fine, but when accelerating it "bucks" then seem to run fine a different rpm, but at some other rpm it is like it would misfire... It is hard to describe the noses it makes!<br /><br />The fisrt time it did that, I replaced the plugs, which I really don't think they needed to be changed (it didn't solve the problem!) the gas / oil is new, the cap vent is open. the fuel hose is o.k. as is the filter.<br /><br />Thanks for helping.