Motor won’t stay running

I have some more information, I think I’m lean towards what I think is wrong but I hope I’m wrong.
The motor now will stay running, but runs very badly. I switched carburetors. That seemed to help a little.BUT When I took the carburetor off the motor, there was oil between the carb and intake ( base plate ) on the gasket. I’m hoping it’s a bad PVC but I’m leaning more towards a ring issue which sucks because it’s a brand new motor. Help me out guys.