toro mower18" starts easily but dies after a second, pull the ropes starts again

This mower is 28 years old been sitting for ever. Pull and cleaned carb with spray cleaner, replaced needle and seat,primer blub and spark plug. Replaced fuel line checked to make sure fuel filter inside tank was not gumed up an fuel flowed steady. This carb had no adjustment other than float. Ran a thin copper wire through all orifices.I'm at a loss thanks