This is a 1967, 3 hp Johnson outboad motor. It runs, but won't gain revs unless I hold my finger over the air intake to restrict the airflow. What do I need to do to operate normally without restricting the airflow?

Your carb needs cleaned well because it has excessive varnish build up from leaving fuel in it long term.

Hi,
Find your air leak. It is getting air from somewhere else.
Peace,
Clarke