Verify that the throttle linkage moves freely. Start the engine and allow it to idle. Detach each vacuum line from its respective port and note whether vacuum is present or not; open the throttle a little and note again whether there's vacuum present. Compare your observations to the accompanying tables for throttle body vacuum lines on 1979 through 1981 models, ensuring that the "8," "6," and "*" stamped onto the throttle body next to each port match up with the same number on the line when reattaching. If a line fails to indicate vacuum when it should, remove the throttle body, clean it thoroughly, and re-check it. If the numbers on the vacuum lines aren't visible, mark them with pieces of numbered tape before detaching them. Drain the cooling system and disconnect the battery ground cable, taking caution if the stereo is equipped with an anti-theft system before detaching the cable. Clearly label, then disconnect any hoses from the intake duct, remove the bolts from the bracket that attaches the duct to the valve cover, loosen the large hose clamps, and disconnect the intake air duct. Detach the accelerator cable rod from the throttle linkage and disconnect the TV cable if applicable. Clearly label, then detach the coolant hoses and vacuum sensor hoses, remove the four retaining bolts, and detach the throttle body and gasket from the air intake chamber. Clean the throttle bore and check for cracks in the body and obstructions in the ports. Check the throttle valve for smooth operation and the throttle valve shaft for excessive play, ensuring there's no clearance between the stop screw and throttle lever when the throttle valve is completely shut. The throttle position sensor should be checked and adjusted. Installation is the reverse of removal, ensuring all air, coolant, and vacuum hose connections are tight, followed by refilling the cooling system and checking for leaks.