First step toward the process of replacing the upper intake manifold is followed by releasing the fuel system pressure and by disconnecting the negative battery cable from the remote ground terminal. Pull off the air filter housing, and then gather all the connecting hoses and electrical connections of the intake manifold and the throttle body then detach them and label them. Third, unbolt the EGR pipe from the upper intake manifold and, then, take off the brackets mounted on the throttle body and on the right side of the upper intake manifold. Finally, turn the upper intake manifold bolts anticlockwise, starting from the outside bolts toward the inside, then take out the upper intake manifold. Remove the gasket and clean the surfaces to where the lower intake manifold will be mounted as well as the upper manifold of any debris or deposits; the rubber O-ring gasket should still be good, and you just re-use it. Put the gasket into the groove in the upper intake manifold and then put the upper onto the lower intake manifold and tighten the bolts in a star pattern from center bolts. For the lower intake manifold, you should first drain the cooling system and the upper intake manifold: make sure that the engine is cool. Remove any hoses, which are still connected but get in the way of the removal of the lower intake manifold then remove the fuel rail and injectors, also remove heater and coolant hoses. Tighten/Loosen the rest of the manifold mounting bolts/nuts in rotational order of 1/4 turn each time until you get to the torque that allows you to turn the bolts/nuts by hand, and then move aside the ignition coil capacitor. Deposits may adhere the manifold to the cylinder heads and it may be necessary to exert some pressure to separate the two with pry bars but refrain from using pry bars to prise between the manifold and the cylinder heads as this may cause significant damage. Flip over the manifold, the pull out the heater supply tube and then change the O-ring with a new one. Scrape of all the remains of the gasket and sealant deposits on the manifold and cylinder heads and clean the mating areas. RTV sealer should then be applied around the front and rear cylinder head water passages before putting down the new gaskets, RTV sealer should also be applied around each of the manifold side of the gasket where the water passages are. Adjust the manifold into its appropriate position over the cylinder heads' ports then fix the rail and the injectors onto the lower manifold and then the manifold mounting bolts with an ignition coil capacitor. Last but not the least, increasingly twist the nuts/bolts to allow more contact between either and the threads; this should also be done in a number of ratchets till the completion of operation is done in the sequence of the removal of the part. With the cooling system empty, refill it, start up the engine, crank it and check for fuel, vac and coolant leaks.