When it was new, my 2011 G5 fuel injected RE idled poorly and at speeds of 30-45 mph it seemed to "surge" too.
By "surge" I mean it would feel like it was accelerating slightly and then decelerating slightly, over and over.
I mentioned it to the members of the forum and they suggested that I change the spark plug from the BOSCH WE7DDC4 twin electrode that it came with to a NGK BPR6ES single electrode plug.
I changed the spark plug as suggested and the idle problem got much better and the "surging" went away.