Transmission will not shift to forward gears?

Car would shift through all gears but as soon as I slowed down it would shift into 2nd gear and stay there. I stop the car and shut the engine off and the car would shift fine through all gears until slowing down and then shift into 2nd again. I replaced the input and output sensors. No help. I replaced the transmission solenoid and now the car will only reverse. When put in a forward gear the transmission locks up.