There could be a screw adjustment for that motor that sets the low speed mixture, lean/rich. If it won’t run at low speeds that adjustment could be all the way in closing off fuel at low speeds.
Ah ha …
Part number 320514 (also listed as 0320514) corresponds to the Tilt Lock Lever and Shaft assembly for Johnson and Evinrude 9.9 HP and 15 HP outboard motors.