Check the throttle linkage for smooth operation; if it binds, the issue may stem from sludge buildup behind the throttle plate due to the PCV hose routing crankcase vapors into the plenum/intake manifold. This buildup can sometimes be cleaned by removing the duct between the air flow meter and the throttle body, opening the throttle plate wide, and carefully wiping out the sludge with a shop rag. If the problem continues, the throttle body must be removed and thoroughly washed in carburetor cleaner or solvent. Remove the hose from vacuum port N and, with the engine running, check for vacuum with your finger; if there is none, the throttle body needs to be removed and the vacuum ports blown out with compressed air. Disconnect the cable from the negative terminal of the battery, remove the duct between the air flow meter and the throttle body, and disconnect the throttle return spring. Use a screwdriver to pop off the link rod from the throttle linkage. Label and disconnect the four vacuum hoses on top of the throttle body, loosen the hose clamp, and disconnect the vacuum hose from the auxiliary air valve. Disconnect the vacuum transmitting valve hoses from the dashpot diaphragm and the auxiliary air valve, and label and disconnect the two coolant hoses from the auxiliary air valve and the throttle body. Remove the vacuum transmitting pipe bracket bolts from the throttle body and the intake manifold, pry the spring clip loose, and unplug the
Throttle Position Sensor electrical connector. Remove the four throttle body mounting bolts and take off the throttle body. Thoroughly remove old gasket material from the plenum with a razor blade to prevent air leaks when reinstalling the throttle body. Wash all residue and sludge buildup from the throttle body with fresh solvent or carburetor cleaner, paying special attention to the throttle plate area, but avoid immersing the throttle position sensor in any cleaning fluid to prevent damage. Blow out the vacuum passages with compressed air if available, and installation is the reverse of removal.