Idle goes up on its own

I'm not familiar with your car in particular, but I know when I've experienced idle rev issues it tends to be an idle air control valve, throttle position sensor, or otherwise something with the throttle body. Again, unsure on your vehicle, but generally speaking it should be a pretty easy fix. If the above is correct for your car, take the throttle body off, clean it up with brake cleaner, clean the IAC valve (or replace it) and replace the throttle position sensor. It'll over rev a whole bunch at first while your computer adjusts to a suddenly clean intake situation, but in my experience it settles down fairly quickly.