Bart, it sounds to me that something is restricting the fuel. You may have some dirt or gunk in your float needle valve that is not letting enough fuel go in. If the Start Your Engine / Seafoam doesn’t dissolve the crud, you maybe looking at pulling your carb off and cleaning it.
Make sure the choke is all the way open as well… if that doesn’t work.
Pumping the primer or closing off the chock might force it to let loose and get you going… HOWEVER, as much as you’ve run through it, it would be a long shot that it will simply fix itself.