I will be at the shop in the morning and look up the specs on that motor. If anyone else has the answer tonite go ahead and answer.
Have you tried a different fuel system? Just to make sure the problem is not in the fuel system.
I am sorry my responce yesterday was posted to the wrong question. Then you opted me out so that I could not respond.
You are right one of the reasons why it is vibrating so bad in neutral could be because of a bad motor mount. Yes once that is repaired then you should remove the gearcase and install an alignment tool to check that everything is square.
Marine Mechanic
marina owner for 20+years, certified Evinrude tech