hi i have a 48 hp evinrude 1989 i bout it new and the company i bout it from could nevre get the idle right thay tryed to do it on muffs then i told them to tank tune it seem beeter for years now it a had compreson test done it was 140- 150 it runs but idel seems a littl off a shop told me that hoever work on it keep on moving my timeing all the way out at its max is there any way i can get it back to were it needs to be o ya 2 years a go thay did carb rebuild but never told me timeing was off please any help thanks