On this model, the upper intake manifold (plenum) can stay connected to the lower intake manifold to do this repair, so you don't have to remove the upper section. Also, something to keep in mind is that when you remove the push rods there are 2 different lengths; if you get the wrong ones in the wrong places the engien will not start so you will want to lay them out in order so they can go back into the same lifters that they came out of.
Here is the replacement procedure for the intake manifold gasket:
Remove the air cleaner outlet duct retaining wingnut
Disconnect the IAT sensor harness connector
Disconnect the vacuum hose from the intake manifold, if equipped with A/C.
Disconnect the power brake booster vacuum hose
Drain the coolant. Remove the radiator inlet hose at the water outlet. Remove the heater hose from the intake manifold.
Remove the water pump inlet hose from the intake manifold.
Disconnect the following electrical connectors:
Disconnect the PCV hose assembly from the intake manifold and the valve rocker arm cover.
Remove the clamp bolt for the EGR valve inlet pipe.
Remove the EGR valve inlet pipe from the intake and the exhaust manifold
Remove the distributor
Remove the serpentine
Loosen the nut for the power steering pump rear bracket at the side of the engine
Remove the Secondary Air Injection (AIR) reactor pipe bracket nut from the power steering pump rear bracket front stud, if equipped.
Remove the nut for the power steering pump rear bracket at the front of the engine.
Remove the bolts and the nut for the power steering pump mounting bracket
Slide the power steering pump bracket forward to access the bolt at the front of the intake manifold.
Installation is the same process in reverse. When installing the intake manifold to the engine, tighten the bolts in sequence starting from the center of the manifold and working outward to the ends. Tighten them in 3 passes; first to 27 inch/ lbs, next pass to 106 inch/lbs, and the final pass tighten them to 11 ft/lbs. This is extremely critical; too loose and it will leak, too tight and the gasket will be damaged.