For an 07 model, it seem's premature to replace the plugs at 40,000 miles on it. It's likely the original plugs or one of them was just faulty. The modern engines uses the platinum spark plugs that's supposed to be good for 100,000 miles. To ensure the correct plugs to use, look under the hood or engine compartment for a white factory label. It will have emission specs, spark plug gap spec and spark plug part number. You will need a spark plug gap tool, spark plug socket, 3/8's -4inch extension and a ratchet. On a 3.7 liter, the coil is bolted with a 10mm on each individual sparkplug, so you will need to unplug each one then remove the 10mm bolt to gain acess to the spark plug..There is no sparkplug wires, cap or rotors on these engines to worry about instead, they are monitored by means of a cam and crankshaft sensor.Service on these sensors are not required unless they fail. The throttle body has some sensors mounted on them so be carefull not to spray any harmfull solvents while cleaning it. IF it has an ETC motor(electronic throttle motor) instead of throttle cables, make sure the ignition is in the OFF position otherwise, you will find your fingers trapped between the throttle blade and housing, it will pinch you. Make sure you gap the sparkplugs according to specs. found on the white label i mentioned earlier. The air filter replacement does not require any tools, simply snap off the retainers and slide the uppper half cover off to gain accces to the air filter. The PCV is semi loaded with a spring and a plunger. If during inspection you find debris inside the unit, replace it. Shake it up and down and listen for the plunger moving, if it doesnt move, replace it. The fuel filter is NOT seviceable as an individual unit. It's part of the fuel pressure regulator thats also part of the fuel pump module mounted on the fuel tank. No service is required on this unit unless you experience fuel delivery issues. I hope this helps.