2009 Chevrolet Colorado -Speedo and Trans issues

speedometer is too fast and trans shifts too soon

How do you know the speedometer is off? I compared the speedometer in my Corolla to what was displayed on my GPS. My speedometer is 1 mph light at just about any speed (i.e., it reads 50 when the car is going 49, etc.) A good shop can recalibrate yours if the error is excessive. That may correct the transmission problem as well.