550 ex won't stay running

I have that 550 ex with auto choke and the new plastic carb. It would not start after a few pulls. So I pulled the spark plug and put some gas in the cylinder and tried that. It fired up but quit running after gas ran out. So I did all the diagnostics. I followed the fuel line from tank to carb to make sure fuel was getting to it. That was ok. So I took the carb out and took it apart to check for dirt and it looked clean but I made sure all the little holes were clear and put it back together tried it again and it fired but just won't stay running. So with the auto choke is there an adjustment that may be out of whack or is the throttle/governor off a little? I don't know why I am having this problem because I ran the mower last fall and after I was done I ran the mower until the tank was empty and the mower shut off. Any ideas? Thanks, Bill

I’m thinking you still have carb issues. If it fires then dies the choke sounds like it is working at cold start.

The first couple of fires are due to the pilot circuit then the main jet takes over.
In your case the main jet is not taking over.
The other silly thing that can happen in the off season is some critter builds a nest in the exhaust so check that the exhaust is clear
Put your finger over it while pulling the starter ( a second pair of hands really helps.