Bike stalling when idle

[IN54NEBIKER]

My Suzuki GZ250 has been in storage for the past year. Whenever I slow the bike and stop, the engine sounds like it is struggling, then splutters and stalls.

Is this a carburetor problem?

I have:
- Drained the fuel tank and topped it up with new fuel (before riding it again for the first time after it was in storage)
- Taken the fuel tap out and cleaned it
- Cleaned the spark plug
- Topped up the oil
- Cleaned the air filter

Any help would be useful...