in the olden days it was pretty common for a car with a healthy cam to hunt around a bit and surge slightly at idle, kinda went with the territory of rumpity rump rump choppiness from a cam with a lot of lift and overlap... I would think modern cars that are finely tuned would get around this mostly, but maybe it's possible that with a bigger more radical cam that the idle quality may never be stellar or perfectly smooth? with a larger cam the engine can sometimes make very little vacuum at idle and not be rock solid stable at idle, especially when trying to keep the idle at well under 1k rpms too...
if you hold the rpms up to ~1k does it stabilize?