RPM's bounce when I start car
 

I recently purchased an Outlander V6 3rd row (Limited version in Mexico), however I noticed that when I start ir every time the RPM's bounce around from 1000-to 1800-down to 800 and back up and so on. It o lt stops when I put it in drive. I have no idea what could be causing it.
I also noticed that my oil level is high and that there is also an oil leak since I have seen stains on the floor where I park, however I don't know if these two events are connected. The car doesn't overheat, drives smoothly (no pulling or tugging) but does tend to shake a bit while idle (it stops if I put the car in neutral). No odd sounds or anything else.