Make sure the nuts that mount the carbs to the manifold are tight and check that the choke and throttle valves are operating correctly. Make sure there are no air leaks in the fuel lines and connections to the engine. A rebuilt fuel pump goes a long way too! These are some easy things to check, the fuel pump is around $20 or less to rebuild, if it hasn't been it is a good idea to rebuild it so it does give the proper flow of gas to the carbs.