Problems with my 1989 Corolla 1.3l carburetor (one of the complex variable venturi ones). The…

Problems with my 1989 Corolla 1.3l carburetor (one of the complex variable venturi ones). The specific issue I have now is to do with the automatic choke.

Symptom: When I let go of the gas pedal, the engine revolution stays high for a couple of seconds before coming down. After a investigating under the hood, I see that the fast idle screw rests against a movable plate and when I press the gas pedal it moves forward along with the screw and when I let go the screw goes against the plate, thus keeping the revs high. After a couple of seconds the plate slowly goes back to it's original position and the revs go down.

Temporary solution: I got the problem at the beginning of the summer and solved this by just turning back the fast idle screw just so that when I release the gas pedal, the screw wouldn't reach the moving plate.

This did however basically disable the fast idle, which wasn't a problem in the summer, but now it's getting cold and I'm starting to have problems starting the car.

THE QUESTION: What is making that metal plate move and what could be the problem. I presume that the plate is supposed to be forward when the engine is cold and back when the engine is warm so that the fast idle screw would only have effect when the engine is cold, however I can't seem to find any information on how the system is supposed to work and how to fix it. I'm great with DIY fixes, but I can't fix it if I don't know what the problem is.

For clarification: the moving plate is always back and moves forward when I press the gas pedal and moves back when I release the gas.

Any information that you have is welcome.

those carbs stink big time. We used to throw em away all the time and put on much better italian Weber carburetors. See if you can find one, those carbs are pretty much useless to fix at that age.