what is the gap for spark plugs in an 04 Matrix?

Correct gap range for these is 0.039-0.051. This is an acceptable range, I typically gap towards the tighter end to allow for plug wear. A tune-up on most newer vehicles is typically just plugs and an air filter. Many vehicles no longer have a PCV valve, and many also have switched to a high energy coil instead of distributor cap and rotor. In addition, some new vehicles no longer have a separate coil at all, instead each of the wires has a coil in the head of the wire, so plug wire replacement is no longer necessary. Depending on your vehicle, you may need to replace plug wires, but I suspect not.