[GuyO]

Jon75 makes a good point. Sometimes the carb idle is leaned out too much - even when shipped new. It is the easiest thing to do first is adjust idle mixture. Also last year after running on the dyno I had to re-jet a 1406 for a brand new 327 because it was still running too lean during break-in. I'd go after the idle mixture first, choke adjustment second then fuel source then rejet as a last resort providing good fuel delivery from the pump.