You really didn't provide a great deal of information about the problem (i.e. first time occurrence vs. long term issue, other unexpected issues, etc.). However, assuming it's related to a recent event, I would chase a percolation problem. I experienced a similar issue, and after chasing numerous potential areas of concern, I installed a 3/4" phenolic spacer under the carb and the problem was solved. I used a full 3/4" spacer but, depending on your engine, manifold, carb package, you might have to use a thinner model. The phenolic material provides a good heat insulator between the manifold and carb and is not affected by gas or
oil. I believe the cost was around $25 and included new gaskets.