The carb insulator boot is one of the most overlooked sources of tuning issues. Over time and with the added stress of heat, the rubber intake boots will tend to harden. They may be fine if your carbs are never pulled out of them, but as they age they lose the ability to stretch and flex-back to shape.
If you have never replaced your intake boot, It's high time you DID!
INSTALLATION TIP! When installing your new intake boot, put a bit of grease on your finger and apply a thin film to the inside surface of both ends of the carb boot. This makes installation a breeze and you wont be fighting friction! applying some heat from a heat gun to make them warm also greatly reduces the amount of force required to install your carbs in them.
When removing the old boots, the heat gun will be your best friend!