'98 transmission/speedo problems

98 auto escort. Speedometer started going all over the place on highway. Then the car was trying to downshift into a lower gear and hunting. Now the speedo has quit all together and the car will stay in first way too long before finally moving thru gears with a little slip here and there. Finally the check engine light came on and it drove a little better, but still no speedo. Any idea's how the speedo and transmission hunting/sliping could be related?