Why does my speedometer stay at 140mph when I'm not going that fast?

What is your question?

It doesn't happen all the time, and I used to be able to turn ignition on and off and it would reset to normal. Now today it goes ahead instead of backwards

What makes this problem better or worse?

Started out when it was damp out, until today

How long has your 2008 Pontiac Torrent had this problem?

6 months