The warning signal for engine lights up

When the key is put into the ignition of the car n the speed of the car decreases. When i start up the engine there is a warning signal for the engine on the dashboard an doesn't disappear. the car is an automatic so when i shifted the gear into 'D' for drive the acceleration is slow n the car felt heavy n when i drive the car up a hill it will slowly decelerate n eventually will not move. Then id switch off the ignition n then start it up again n the cqr would do the same thing all over again.