You will need to remove the air intake duct, inspect the
Throttle Body bore and the throttle valve plate for deposits, then clean the throttle body bore and the throttle valve plate using a clean shop towel with GM top engine cleaner, GM P/N 1052626 (Canadian P/N 993026) or AC-Delco Carburetor Tune-Up Conditioner, P/N X66-P, or an equivalent product. Finally, you can install the air intake duct.