What is the reason for the engine jitter of BMW n20b20 after replacing the water tank?

There are many reasons leading to engine jitter, such as damaged machine foot pads, lack of cylinders, carbon deposition in combustion chamber, carbon deposition in throttle, etc. If the engine is shaking, you should check what causes it and then repair it. There will be carbon deposition when the engine is used for a long time, because the combustible mixture can not be fully burned in the engine, so carbon deposition will occur in the engine after a long time. "