Decrease the fuel system pressure. Disconnect the wire from the negative terminal of the battery. At front, lift off the engine cover and then slide it to the front end. Remove air filter housing and intake air duct. Take off vacuum hose for brake booster and PCV hose. At every injector unplug electrical connectors, take out injectors with fuel rail, and undo all connections from throttle body. On some models where necessary for clearance, A/C compressor can be removed leaving refrigerant lines connected and put aside. All interfering sensors must have their electrical connectors detached. Lastly, remove wiring harness support at back manifold as well as shifting line side also eliminate air conditioning line support clip. Place the alternator aside after separation from it.Remove throttle body bracket if one fitted.Loosen intake manifold mounting bolts until you can remove them with your hand in quarter turn increments using same pattern as tightening sequence .After sliding forward remove intake manifold ; also disconnect any other connectors including MAP sensor etc . While lifting manifold from engine note anything still attached /disconnect it ,throttle body can now come out if desired (note that mating surfaces of cylinder heads and intake manifolds must be perfectly clean when installing manifold). Examine o-rings on intake manifolds for damage or hardening; if they are good they may be reused but new ones should be installed if needed ensuring perfect fit into grooves provided.Gently lay down manifold.CAUTION! Do not disturb rubber seals or move manifold forwards or backwards after contact is made with cylinder heads because seals might dislodge resulting in vacuum or oil leakage by engine through these faults. Install intake manifold bolts following correct sequence by tightening to torque limit without overdoing it .The rest of installation is reversal.Air leaks within manifold joints should be inspected with care after switching on the engine.