Car decelerate while driving

Maintenance/Repairs
1

I’ve a Honda Accord ES 1992. While driving at a steady speed around 30 miles/hr, there are time the car did seem to decelerate. I stepped on the gas but the RPM decrease instead of increase. At this point the car also decelerate. On other hand when I got it to go around 55-60miles/hr, the car seems to be sputter or had a little hick up along the way. Pls tell me what is wrong with the car.