For 1990-2009 cars

Caution: Do not insert any tools into the throttle body bore in order to avoid damage to the throttle valve plate.

Caution: Do not use any solvent that contains Methyl Ethyl Ketone (MEK). This solvent may damage fuel system components.

1. Remove the throttle body. Refer to Throttle Body Assembly Replacement.
2. Inspect the throttle body bore and the throttle valve plate for deposits. You must open the throttle valve in order to inspect all of the surfaces.
3. Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM Top Engine Cleaner P/N 1052626 (Canadian P/N 993026) or AC-Delco Carburetor Tune-up Conditioner P/N X66-P, or an equivalent product.
4. Install the throttle body. Refer to Throttle Body Assembly Replacement.