I have a lowe 1940 v and a evinrude 1987 v4 110hp with a jet pump. My engine runs good at high rpm (5300 plus) and at low rpm (less than 1000) but at about 2500 rpm up to 3000 or so it develops a miss. I took it out 2 days ago and noticed that if I trim the engine up that the miss goes away. Could this be a float issue? Is it normal to have to trim jet pumps. I was told that the system should be vertical for proper operation