i've been scratching my head on this one. the car starts up fine and idle decently. what i find is when the car is put into reverse and starts to roll after lifting the brake, the rpm will start to swing/surge. i don't think the swings in rpm has caused it to stall yet.
i have a 6.0L with LS3 top end and a 4l80e with a 3200 rpm stall