The upper intake manifold, referred to by Toyota as the intake air surge tank, requires the disconnection of the negative battery terminal, removal of the engine cover, and the air intake duct along with the air filter housing. Next, coolant hoses from the throttle body should be clamped off and disconnected, followed by the disconnection of the EVAP system fuel vapor feed hose, ventilation hose, and throttle body wiring. Two Vacuum Switching Valve electrical connectors need to be disconnected, and the throttle body bracket bolts should be removed to take off the bracket. The baffle plate must be removed, along with both bolts from each intake manifold support bracket, which Toyota calls surge tank stays, before removing the two intake manifold mounting nuts and four mounting bolts to detach the upper intake manifold. The condition of the upper intake manifold gasket should be checked, replacing it if necessary, and installation follows the reverse order of removal, ensuring that the mounting bolts and nuts are tightened to the specified torque. For the lower intake manifold, known as the intake manifold by Toyota, the upper intake manifold must first be removed. If replacing the lower intake manifold, the fuel rail should be removed; however, if only replacing gaskets, disconnecting the fuel supply and return line connections is sufficient. The lower intake manifold bolts should be removed to detach the manifold, and old gaskets must be discarded while cleaning the mating surfaces thoroughly. Installation is again the reverse of removal, using new gaskets and ensuring the bolts are tightened to the specified torque.