Driving in traffic is worst as as whenever I stop vehicle, the engine stops and it needs to be restarted again. What can be the issue? Facing this problem since an year now.
Perhaps the carburettor needs cleaning, in particular the slow running jet. There are Youtube videos you can find, such as this one.
Absolute cleanliness is essential, as well as a clean tray to keep the parts in.
The bottle probably contains petrol. Don't use metal things to clean it, only soft things. In the video, petrol is squirted through the jet. I used to use (literally) a cat's whisker to clean it.
No naked flames.