Have you tried giving your idle air control valve a clean? It's located underneath your throttle body and if it's dirty it causes the idle to become high. The best thing to do is take the throttle body off, remove the screws for the IACV (apply a lot of pressure as they're quite easy to round due to old-age) and give it a wipe with carb cleaner. Alternatively, you can spray the cleaner directly into the small hole at the opening of the throttle body (so you don't have to take the whole thing off), but it's important to wait a while until the cleaner has dried before starting/driving the car. The idle speed for the 4A-FE, 5A-FE and 7A-FE is controlled by the ECU, so there's no adjustment screw as such.