It could be the Idle Air Control (Idle speed control) valve. Its located on the left side of your TBI and has an electrical connection.
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Turn the Idle Adjusting screw.
on top of the upper intake there is a screw. it can be used to adjust idle speed.
Computer controlled? Not adjustable
There should be an idle screw right by or under your throttle
The idle speed on a 1987 Chevy Celebrity is controlled by the engine computer, there is no way provided to adjust it.
1990 gmc p/u 5.7 wont idle showing code 12
Chevy did not use an Idle Air temperature sensor on that year.
there is a screw on the carb right where the throttle cable hooks to it that you use to adjust the idle.
The idle is control by the idle air control motor from outputs from the Engine Control Module.
Actually, it should be don e with a vacuum gauge, to maximum vaccuum. Without one, adjust the idle mixture to max., idle.
You can not adjust the idle screw, it is sealed off at the factory. If you are having a high idle problem check for a vacuum leak or a bad idle air control valve. These will commonly cause a high idle.