The car shuts off at the stop light, shakes roughly, and sounds like it's low on power when the engine is warm. When it's cold, the car runs perfect. When we tried cleaning the carburetor with the can cleaner (as directed in the can) the engine got too hot really fast. Prior, we replaced spark plugs, spark plug wires, fuel filter, and air filter. We tried a couple of mechanics who checked the engine and didn't notice anything. One saw that one of the pistons wasn't moving, but the next day it moved like normal. What could be the cause of the problem and how do we fix it?