If you have an older car, or a performance car, you most likely have a carburettor that is possibly made by Weber. While all carburettors work very well when they are clean and in tune, they can quickly cause running problems if dirty. Fortunately, carburettors are very easy to clean and get running properly again. It only take a couple hours of your time and some patience.
Open the bonnet and locate the air cleaner on top of the engine. It is usually round with a wing nut on top. Remove the wing nut, air filter and cover and place them on the ground next to the car or in some other safe place out of the engine bay.
Spray a small amount of the carburettor cleaner into the throat of the carburettor being sure to coat the entire inside. The throat is the small hole in the centre of the air cleaner housing still attached to the engine. Allow it to sit for about 5 to 10 minutes.
Use your finger or a small brush and rub off any carbon or dirt visible. Use some more carburettor cleaner to rinse off the loosened dirt. Wait another 5 to 10 minutes. Remove any rags or tools from the engine, then start the car. It should run at a high idle for a few seconds while the cleaner burns off. Once the idle stabilises, the engine should run better. If not, repeat the cleaning process.
Reinstall the air filter and cover, and finger tighten the wing nut.
There are many different carburettor cleaners, research which ones work the best. If the cleaning does not help the drivability, the carburettor may need to be rebuilt or you may have a different issue altogether.
Do not drop anything into the carburettor throat other than the cleaner. This opening goes directly into the engine and anything else would cause serious engine damage.