2007 150 HO bought new has had a problem from the beginning , runs rough between 1500 and 2000 rpm , and will stall if I throttle down from the start . Runs great over the 2000 rpm mark . Just had a 300 hour service done and they tell me that it is common for this motor , are there any fix's for this problem , I have lived with it for this long but it would be great to throttle down and not have to baby it over the 2000