4A-C Engines

[Pugho]

Jaimemirror is on the right track.. I've had a couple of AE82's with this engine and I know they have a little vacuum diaphragm called a "dashpot" on the carb.
Pop the hood and remove the air cleaner so you can see the carburettor. Then start the engine and rev it by turning the throttle directly on the carburettor instead of pushing the pedal. When you let the throttle go, watch as the dashpot moves up and "catches" the throttle on its way down.
As said, it is an emission control device that is supposed to make your emissions cleaner.