Small Engine Troubleshooting Problems? Ask a Mechanic Now.
This is the briggs twin OHV engine. Need to run a cylinder balance test. Loosen the spark plug wires and with the engine idling, remove one wire at a time. If the engine dies when wire is removed, the opposite cylinder is not firing. If not firing, check it for spark and compression. If it has spark and compression and still will not fire, check the valves on that cylinder. May have a pushrod off. With just one cylinder firing, it will be hard to start and have lack of power.
Did you run the cylinder test when engine was hot and has lack of power?
OK, let's look at the start issue, is the choke flap in the carburetor closing completely when you go to the choke position? The throttle max is choke position?