Mantis Tiller Carb problem

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Got a 4 year old Mantis. Got the c1u-k54a zama carb in it. It will start and run for 5-10 second and die. Choke pull, un choke pull and it starts again for 5-10 seconds. It won't stay running. I replaced the gasket and diaphrams and have reinspected it three times, still no luck keeping it running. I replaced the brittle fuel line. It's getting fuel so the filter is ok. When I'm running it for those 5-10 second rounds, I can choke it/un choke it and keep it running. But the choke lever is not the throttle. This carb is so simple, what could it possible be? Help me please. It'll probably be cheaper to buy a $60 carb rather than take it in!!!