I think its a leak

Ok I have an 82 440 and just broke it back out from the winter. I had trouble getting it to start and run so I replaced the plugs (which were shot) and pulled the carbs and boiled the hell out them and blew them out pretty well. They are now sparkly. Anyway I have still having troubles with the left carb. It is backfiring randomly and it is slow to return to idle after acceleration. Also the exhaust from the left pipe is coming out with less pressure than the right, although it only a slight difference. When I squeezed the boot going into the engine it seems to run smoother for a bit. My guess is that I have a leak there. Any suggestions on how I can confirm/find it. I was thinking about using some silicon caulk around the boot and carb to seal it. Do I need to get a special kind or will any Home Depo stuff work.

Warm up the engine and set the idle down as low as possible; spray carb cleaner around the carb holders; if the idle changes or the engine quits you have a carb holder leak. If so, replace them. You can spend a lifetime playing with caulk, but it will never work as well as new carb holders because it only takes very tiny leaks to effect the idle. There's a lot of vacuum in there when the throttle is closed. Ed

thanks a ton, I'll try that tomorrow.