this is usually a misfire

Do you get check engine light on? Oh, I see, your car is 1989 so there is no check engine light.

It could be many things, such as ignition, engine compression,fuel. or restricted exhaust.

the easiest thing to do is to do a tune up by changing spark plugs, wire set, distributor cap and rotor. Then you can add some fuel injector cleaner into the tank.

Timing belt could be problem too if is has too much slack causing poor compression.