Josh,
From your description of the way the engine dies, we presume it is starting on and running for a second on choke-supplied fuel, but once that fuel is consumed the engine is not pulling more fuel up to keep it running.
Your efforts appear to have been quite detailed, but as they did not assure proper operation of the engine, there may be some cause which apparently is not just in the carburetor.
If your continued efforts do not effect an improvement in the run time of the engine, we can only suggest you get the unit to an authorized Briggs and Stratton engine service dealer and allow him to effect a thorough evaluation of the condition.
I have the same mower with the exact same problem. If I prime the motor, start the motor, then continue to prime the motor for about 5 minutes to keep the motor from stalling, it will eventually continue to run on its own. I know this is definitely not optimal, but it got me through the day.
Please keep us posted if you find out the cause and the fix.
Josh,
From your description of the way the engine dies, we presume it is starting on and running for a second on choke-supplied fuel, but once that fuel is consumed the engine is not pulling more fuel up to keep it running.
Your efforts appear to have been quite detailed, but as they did not assure proper operation of the engine, there may be some cause which apparently is not just in the carburetor.
If your continued efforts do not effect an improvement in the run time of the engine, we can only suggest you get the unit to an authorized Briggs and Stratton engine service dealer and allow him to effect a thorough evaluation of the condition.