speedo issues
 

I have a 2002 liberty with 3.7L V6. The speedo goes haywire (bounces between 0mph and my actual vehicle speed.) when when I take my foot off the gas peddle. The crouse control doesn't work properly while the Speedo is acting up. I think it could be the speed sensor, or a loose electrical connection. But I'm not 100% sure. any thoughts?