What would cause a car to stumble at wide open throttle? Such as flooring it to go around someone on the highway, or even from a stop sometimes. I step on the gas and it either does nothing or sort of bucks for a second, then takes off. No CEL either. I scanned for codes, and only got EGR insufficient I believe it was. This does not happen every time, seems like the car only does it when I need to get out of the way, and it decides nope.

Thanks!