Damned FixYa ate most of a detailed post.

If Briggs & Stratton, it will likely have two adjustment screws on the carburetor. One is for low speed, the other for full load.

Take note of how far you turn them so can return them if needed.

From your description, using the choke normally means the engine is starved for fuel so backing off the mix screw might cure it.

If not, then likely one of the jets is fouled so you will have to remove the screw(s), counting the turns as you do.

Clean the seats with carburetor cleaner (auto parts store or Walmart) and replace the screws.

They may still need adjustment after reinstalling.