2018 Mustang GT with manual transmission. Engine stalls when shifting into neutral (manual trans) at higher engine speeds. For example, coming up to a red light (was traveling approx 50mph) or while exiting the freeway (was traveling 65mph and then was turning around an off-ramp). Has occured at any driving speed (if revving engine at full stop, or while traveling). Stalling does not occur if the transmission remains engaged while slowing down. If I shift to neutral when the engine is near it's normal idle speed (500 RPM after warm-up), it will not stall. The problem only occurs when shifting to neutral above ~2,000 RPM, and only after the engine is warmed up. The problem was present from the time the vehicle was brand new. At 1500 miles I returned to the dealer and was able to successfully reproduce the issue together with the service advisor. In some instances, the engine speed will drop below idle speed and then will recover and not stall. I made a recording of the can bus to try to diagnose the issue on my own, which is available upon request. It seems that the engine controller is requesting more torque from the engine when the speed drops, but the throttle will not respond to the request and the engine will stall. No dtcs or warning lights were given to indicate that there was an issue. No modifications were made to the car, and is in completely 'stock' condition.

- Southfield, MI, USA