We have a 2004, with 107K, and a currently blown engine. I am rebuilding. Prior to this, we have consistently pulled 34-36mpg. We were pulling 32 at 97K, with a slight miss, and I replaced the plugs/wires, and it went right back to 35-ish.

The only things I have done are a drop in K&N filter, and Mobil 1 full synthetic since about the 2nd, 3rd oil change.