Ford dealer installed a new battery Thursday. Yesterday I drive truck on the highway at 70mph and I was getting passed by UPS trucks.
I came home disconnected battery and let it sit overnight. I reconnected everything this morning and go to leave and while in park speedo shows 20mph.
I disconnected everything again let it sit for an hour or so. I reconnected and speedometer now shows 30mph while parked.
I went into the instrument cluster test mode and ran the test several times and it didn't help.

 

I'm having the same problem. Did you find a cure?

 

I ended up taking the instrument cluster cover off and physically moved the needle back to zero. I never had another problem. Speedometer was off by about 1mph according to my Garmin GPS.