What is the reason for Toyota Old desert prince's unstable idling and vomiting?

When idling, the engine shakes and the speed is uneven.

The reasons are: the idle air metering hole is blocked, the idle device is not working normally, the spark plugs of individual cylinders are too weak, the seals of individual valves are not tight, the intake manifold leaks air, the ignition time is too early or too late, and the idle speed is not adjusted properly. When the idle speed of the engine is unstable, the idle speed should be adjusted first. If the fault cannot be eliminated after idle speed adjustment, check whether the idle metering hole and idle air metering hole are blocked. If the metering hole is blocked, clean it with gasoline or acetone and blow it with compressed air. If the metering hole is not blocked, to stabilize the engine speed at a certain speed, you can observe whether the middle and lower gaskets of the intake manifold or carburetor are leaking. If there is air leakage, it can be eliminated by fastening screws or adding or subtracting gaskets. If the idle speed is unstable and the engine power decreases, the working condition of the spark plug, the sealing performance of the valve and the ignition time should be further checked, and maintenance and adjustment should be carried out if necessary.