Outlander Problem

I have a 2004 Outlander LS 2WD with a MIVEC engine. My problem is that I've lost about 60 miles per full tank of gas, of mileage. And I also don't "feel" the MIVEC kick in at around 3500 rpm anymore. Is it possible that all the engine valves are open all the time, thus reducing my mileage and preventing me from feeling the usaul thrust of extra power I felt from the MIVEC kicking in at 3500rpm.

there's a couple reasons why this could be happening:

1)
when it gets colder outside your milage will go down. the cooler air is denser so more of it gets sucked in with each induction stroke. then because of that more fuel needs to be injected to maintain a proper air/fuel mixture.

2) for me at least when it get colder (for arizona ar least) i tend to let my car idle when i start it up for a bit longer until the gauge starts to move. not sure how long you get your's warm up for or if it's changed with the weather.

3)
the outlander has a pretty hefty gas tank. so you're prolly only using a couple more miles per gallon, and that can add up over the course of a tank.

4)
check your intake air filter

5)
when's the last time you changed the oil?

as for the mivec thing, i've got nothing for you on that bro. might wanna take it to the dealer and ask them to look it over for you if you're concerned about it.