Speedo not working and transmission not shifting correctly

My 95 Corsica has an issue with speedometer not working and you also have to rev the crap out of it to get the car to shift from 1st into second. After it finally shifts the service engine soon light comes on. Still no speedometer and not sure whether or not it shifts into 3rd or overdrive. You have to manually shift the car after the service engine soon light comes on. It won"t downshift or upshift unless you do it manually. I was told the speed sensor was bad so I relaced it and still nothing. All other gauges work good and the car seems to run ok. One other quirk, upon initial start up when you have to run the engine up to get it to shift the ABS light also comes on and when it does it acts like the car has more power. Any help would be appreciated greatly. Wireing to speed sensor appears okay.