i have a 1996 johnson 15 hp. she doesn't want to idle at all.i have to have her about1/4 to 1/2 throttle to keep her going. I bought the motor and she ran good. so here are my questions. how do i get her to idle better. do i need to adjust the screw on the carb, or the screw on above it to the left of the roller, or the idle adjustment knob on the tiller? or so i need to adjust the linkage all together. i post earlier bout a small outboard mechanic but if it is something i can fix myself i would much rather do that then pay 300-400 bucks for someone else to mess with it. if anyone can walk me through the steps that would be great. if pictures are needed about what i am talking about just say the word the camera is charged.