Engine Craftsman weed eater with ryobi power plant dies after warming up

I just bought a used weedeater. It is a craftsman weed eater but someone replaced the power plant with a ryobi engine. It primes fine on the a choke setting, starts fine on the b choke setting and runs great on the c choke setting for about minutes. Then starts dying. Will hardly run at all on the c setting if you give it gas. Will run at about half speed for 3 or 4 minutes on the b setting then dies. But always restarts immediately.

Any ideas?

Apologies in advance as I am not sure what model ryobi engine is on it and can't find anything with a model number on it related to the engine.

Engine Craftsman weed eater with ryobi power plant dies after warming up