When I drive at more than 55 mph it starts jerking and if I accelerate or step on the gas to overtake somebody it fails... Sometimes it takes a while to start doing this, but obviously it's not reliable if it happens every once in a while.
It might be a problem in one of the coils, that might happen for a loss of electric power in one of the pistons. You might need to use a scanner to tell you which one is the failure