First gear starts and reverses abnormally.

About the question you asked, on the one hand, it may be because the contact surface between the clutch plate and the flywheel and the pressure plate is uneven, which leads to the intermittent contact of the clutch plate in the semi-engaged state, which leads to the failure of the engine and gearbox. In addition, when the engine is idling, the load increases, which leads to the slight knocking of the engine, which easily leads to the formation of carbon deposits inside the engine. This should have a lot to do with the driver's long-term operation. I suggest you check and clean up the carbon deposit on the accelerator, and it is best to initialize the engine computer.