had my 20hp out a few times and all of the sudden when i oen it up and go for a while , <br />every once in a while it acts like it hits something , like a log or stick in the water. <br /><br />the boat jerks a little, and then it runs ok for a while, and then it does it again, every so offen.<br /><br />What causes this?<br /><br />uneven gas flow?<br /><br />electrical fouling out maybe?<br /><br />Thanks...