The carburetor, Throttle Body Injection (TBI) unit or throttle body on multi-port fuel injected models is attached to the intake manifold by four bolts or nuts. These fasteners can sometimes work loose from vibration and temperature changes during normal engine operation and cause a vacuum leak. If you suspect that a vacuum leak exists at the bottom of the carburetor or throttle body, obtain a length of hose. Start the engine and place one end of the hose next to your ear as you probe around the base with the other end. You will hear a hissing sound if a leak exists, but be careful of hot or moving engine components when performing this check. Remove the air cleaner assembly, tagging each hose to be disconnected with a piece of numbered tape to make reassembly easier. Locate the mounting nuts or bolts at the base of the carburetor or throttle body. Decide what special tools or adapters will be necessary, if any, to tighten the fasteners. Tighten the nuts to the specified torque. Don't over tighten them, as the threads could strip. If, after the nuts or bolts are properly tightened, a vacuum leak still exists, the carburetor or throttle body must be removed and a new gasket installed. After tightening the fasteners, reinstall the air cleaner and return all hoses to their original positions.