What is the code p0121 with a red lightning bolt on the dash

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! The P0121 code in your 2010 Chrysler 300, coupled with that ominous red lightning bolt, indicates a problem with the throttle position sensor (TPS) or its circuit. This sensor monitors how far you press the gas pedal and communicates that to the engine control module. A rough idle and the warning light suggest that the TPS might be malfunctioning, or there could be an issue with the wiring or connections around it. Given that it's intermittent, it might also be worth checking for any vacuum leaks or other related components that could be affecting performance. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554!