Today, I was on a highway that was flat, no hills so I decided to put my cruise control to the test. When the cruise was on I noticed that when it got up to 2500 RPMS that it would drop back down to 2000 RPMS. It kept doing that. It kind of made the car jerk a little.

Is this normal for the rpms to keep going up and down while using cruise control.

 

They'll vary a little bit as the car doesn't react to differing loads until after something happens. You can see the road, so you might take your foot off the gas right before you crest a hill to keep you from going really quickly.