what octane?

87' Johnson, 60 hp...........this thing starts and runs beautiful, but about a third of the time when I go to put it in gear, it will die. Starts right back up. Following advice on this board, I use gasoline that does not have ethanol, but I was wondering if it would help or hurt if I went to a little higher octane? I am running 87 now..........have choice of 89 or 93 at the station where I normally fuel up

I stopped by a shop and told a mechanic my plight, he suggested to push the key in to activate the primer if it sounded like it was going to die, and see if that helped..........it did not, if I push in the key, it continues to stall, no difference at all. Its not like I live close to a marina, so I havent made it back to tell him the results.

Its like the idle needs to be bumped up ever so slightly, but I dont have a clue how to do that..............looking for any advice.

thanks,
Sonny

Answer these questions.-----------Where does the tell tale for the water pump exit the block, is it on the side or from the top of the engine block.----------What results do you get from a compression test ?--------Perhaps these questions mean nothing to you , they mean a lot to those who know these motors.