Before embarking on a process of removing the upper intake manifold (plenum), you should turn off the car's fuel supply by loosening the pressure on the fuel pipe and afterward, you should also remove the negative cable of the battery. Pump the coolant into a different container that has been cleansed by washing. Subsequently, take out the air intake duct, detach throttle linkage, hoses as well as electrical connectors from the throttle body. The spark plug wires first have to be disconnected and removed from the spark plugs that belong to the rear cylinder bank and from the retainers on top of the plenum a distributor cap is taken off and put aside together with the wires connected to the spark plug. Remove all the identified hose and electrical connectors from the plenum then unplug those from feasibility fast idle control valve, for a wider access. Two ground straps and the four bolts that hold the breather tube brackets to the plenum must be unscrewed. Following that, you should then pull out the upper intake manifold bolts and then remove the manifold with the throttle body. Try to clean the contact areas of the lower manifold and replace the gasket before fitting the upper intake manifold On tighten bolts to the prescribed sequence and turning the specified amount. For the lower intake manifold, firstly, deal with the upper intake manifold's removal, and then detach the electrical connectors from the fuel injectors, of course, using labels. Loosen and unbolt the coolant pipes at the transaxle end of the intake manifold and then unfasten the lower intake manifold from the cylinder head through the stud bolts without scratching the gasket surface of the manifold. Shave off the previous gasket material and also ensure you scrape the mating surfaces. Take out the coolant pipes to fit new gaskets and place the lower manifold on the engine/block, making sure it sits correctly over the dowels featured on the cylinder heads. After installation of all bolts, and screws to the assemblies, further tighten the nuts and bolts in the following manner: three equal incremental turns to the recommended torque figure where it is mentioned that the nuts' torque capability is different from that of the bolts. Last but not the least, do the final services in the respective order, top up the cooling system, replace the engine oil as well as start the engine in order to check for leakage.