Vehicle Symptom: The vehicle exhibits a persistent rough idle and engine hesitation specifically when at operating temperature. This issue is most prevalent during "Auto Start/Stop" transitions and while idling in heavy traffic. The engine feels as though it may stall, creating a significant safety concern regarding predictable acceleration and vehicle control in live traffic. Safety Risk: The instability of the engine performance creates an unpredictable driving experience. There is a high risk of the vehicle stalling or failing to accelerate properly when restarting from a stop, which could lead to a rear-end collision or leave the vehicle stranded in a dangerous intersection. Furthermore, despite these clear drivability issues and the engine's erratic behavior, the vehicle has not illuminated a Check Engine Light (CEL), depriving the driver of a necessary safety warning regarding these malfunctions.