Spark plug

If your have the 3.5L engine (24 valve) the # 2, 4, & 6 are in the back- under the ignition coil on plug. The # 1, 3, & 5 are beneath the intake manifold upper plenum which has to be removed ( but not the lower intake manifold). Remove the top cover (just pops off) that says 3.5L 24 Valve on it. Remove six long screws in the rear #10 hex heads, and one of the same by the alternator. Disconnect the sensors connectors and unscrew the EGR tube in the back. Disconnect the vacuum hoses and alternator top mount plate. Remove the oil fill tube, and the two screws that anchor the front side of the plenum to the exhaust manifold. Carefully lift up and pull towards the front of the engine making sure you have removed ALL of the attachments to the plenum (there is a black arm on the vacuum modulator that on the rear right side that needs to be popped off gently). Once removed, the 3 coils are easily removed, thou I would strongly recommend replacing the coils also ($38 each at Auto Zone) if you experiencing a misfire. You will also need the plenum gasket ($12) once the plenum is removed or you have vacuum leaks.

Good luck!

See the diagrams below, they will make it clear what needs to be done

You will have to remove the upper plenum chamber, that's the top part of the intake manifold that air goes through on its way into the engine. Its the only way, Its not that hard.