My 2006 Chevy impala speedometer is going haywire when at a stop light, the air keeps switching to the outside air and inside circulation and then blows hot and back to cold, and my display says speed limited to 107mph, when I take off from the red light...the acceleration is lost and then comes back slowly and gradually builds back up to speed The speedometer sensor was changed but it is doing the same thing. Any thoughts of what direction I should go? My transmission guys think it is electrical. I did have some work done... a transmission Fluid Cooler Outlet Line repaired, a power steering pump replaced and silicon oil and transmission pans installed, air coolant in my a/c ...do you think my mechanic knocked something loose during repairs? Thanks in advance!