Fixing my Mariner 2HP 2stroke?

My Mariner can be started without too much trouble, runs for a while, the choke is sensitive, it is hard to get it to idle at low revs....however, once running it goes for a while then cuts out.

Also fuel comes out of what I think is the overflow.
Seems to be something to do with the carburetor, choke or possibly the float (floading itself).
It sometimes has to be left for a while before starting again.
It rarely runs longer then 2 minutes.

I would appreciate some tips from past experience-they are apparently a fairly simple setup.

Any Yamaha or simple 2hp engine will be pretty much identical in design.

Mark
November 2008