Shooting a little carb cleaner into the air intake will do nothing at all except give the motor something to burn in addition to fuel. The problem lies inside the float bowls.
You have blocked pilot jets and there's nothing you can do to properly clean them other than remove the carbs, take out the jets and run them through with a small wire (top E guitar string is ideal. Ernie Ball Hybrid Slinky 009 works for me
).
You can also give your carb cleaner another try while you're in there but don't get it near the throttle diaphragms. Strong carb cleaner - which is different to the cleaner additives you put in the fuel tank - will make a mess of them.
Drop me a PM if you want to talk more about 'Ivanising' ... I could do both jobs at the same time and it would be about the same labour cost as getting a dealer to remove the carbs and clean them.