Hello I have a big problem. I have a 92 honda civic 4 doors . Automatic transmission . When I'm driving it the speedometer got crazzy and go up and down and then stay down but when that happen the last gear [5th] shift to 4th and stay there even when I go over 70 or 80 miles per hour still on 4th gear. But when the speedometer starting to work again then shift to 5th. I don't understand please help tnx.

