- Remove the air cleaner outlet duct.
 
- Inspect the throttle body bore and throttle plate for deposits. You must open the throttle plate in order to inspect all of the surfaces.
 
Notice: Do not subject a throttle body assembly which contains the following  components
to an immersion cleaner or a strong solvent:
|    •  | Throttle position (TP) sensor | 
 
|    •  | Idle air control (IAC) valve | 
 
|    •  | Sealed throttle shaft bearings | 
 
The cleaners will damage the electric components or sensors.
The cleaners will damage some of these components that contain seals  or O-rings.
Solvents can wash away or break down the grease used on non-serviceable  throttle
shaft bearings.
Never use a wire brush or scraper to clean the throttle body. A wire  brush
or sharp tools may damage the throttle body components.
Do not use a cleaner that contains methyl ethyl ketone. This extremely  strong
solvent may damage components and is not necessary for this type of   cleaning.
- Clean the throttle body bore and the throttle plate using a clean shop towel and top engine cleaner, GM P/N 1052626 (Canadian P/N 993026), or equivalent.
 
- If the deposits are excessive, remove and disassemble the throttle body for cleaning. Refer to the following procedures:
 
- After disassembly, clean the throttle body using a parts cleaning brush. DO NOT immerse the throttle body in any cleaning solvent.
 
- If removed and disassembled for throttle body cleaning, assemble and install the throttle body. Refer to the following procedures:
 
- Install the air cleaner outlet duct.