What are the reasons for unstable car idling with fluctuating RPM and stalling?

[DeJaxon]

Scooter idling instability with fluctuating RPM and stalling can be caused by reasons such as deteriorated fuel. Below are the specific details: Idling speed too low: Motorcycle engines can generally start at over 200 RPM, but may stall due to excessively low idling speed that cannot be maintained. Deteriorated fuel: It is possible that the fuel in the carburetor has deteriorated, leading to poor combustion which causes unstable idling and difficulty starting. Draining some fuel through the drain pipe at the bottom of the carburetor usually solves the problem. Nozzle issues: Air bubbles blocking the nozzle can cause unstable engine RPM and stalling. Additionally, using excessively dirty fuel may clog the nozzle, or leaks in the fuel pump and fuel lines can result in abnormal fuel pressure, causing unstable idling.