40c twin carb on a mariner outboard motor question

[travis sparrow]

I'm having trouble keeping my engine running if you choke it and keep it choked it will stay running but as soon as u throttle up or remove the choke it dies out I think my carburetors are stoped up its been setting since 2007 we just got it this year I'm not sure if the guy before us went out and started it or not since 2007. Does anyone think there could be something else wrong that I don't I have changed the spark plugs and filled the carbs and lines full of carb cleaner and let it set for 12 hr but still know change. Any help would be great.

Also. If I have to rebuild the carbs where this motor is 25 yr old is there a way to make it safe to take the bolts out of the carb I am afraid I will break them when trying to loosen them up.