Make sure it is properly sealed up with o2 safe sensor sealant and then on the next run, richen the low end after a minute or two.
It very possibly sounds like an air leak or a low end needle set too lean.
(I just put the two posts together
Also, check to see if the tank is bubbling more than it should. Then you would have a air leak in the tank. Replacing fuel lines would be a safe thing to do as well, since most people don't switch them out often enough.