[larrys40]

Dave
I think Brent gave you the correct advise. Unless you have a sticking valve the marvel oil won’t do anything. It sounds like you need more from the gav carb adjustment which is the dash Choke rod adjustment. Turn it a little clockwise maybe a quarter turn at a time and see if that helps. Too far will make it lope.
Gary noted the carb jets which if the main jet and/or cap jet get clogged can cause issues. Fuel sits at the tip of the jets and if sitting with today’s fuels can clog if sitting for a months or more.
From your description I think it’s your gav adjustment from inside the car, but acheck if the jets would also be in order.
Larry