Bob I just inherited a 68 model johnson outboard 65hp. The motor sat in a garage for 10years before I got it. I've since had all the wires and wiring harness replaced, carb. cleaned, oil change, fresh spark plugs. The problem I have is staying at idle speed with out cutting off. When the motor chokes off I have to pull all the way back on the throttle in order to move the shift lever to neutral. The motor usually won't start with the throttle all the way back. When I can get it started the throttle is about half way up and now the shift lever won't engage. I have to throttle back, quick throw it drive and throttle back up before it chokes out. I have replaced the fuel lines and tanks. Someone told me I should be running high test fuel in my motor. They say older motors were made for leaded fuel and I should run a 93 octane to make up for it. They also say I should be mixing fuel to oil at 50:1. I read that motors before 1970 should be run on a mix of 40:1. Could using low octane and mixing at 40:1 be causing the problem? The motor runs fine right off the trailer. I don't experience these problems until I have to slow down like for a no wake zone. Any advice would be appreciated. I understand I have an antique of an outboard, but it was a gift.