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Discussion Starter · #1 ·
We have a 2WD 1999 Dodge Durango that has about 75K miles on it. It has been a great vehicle as we have driven it on long trips and long moves with very few problems. Prior to now we have gotten around 350 miles to a tank of gas (about 16MPG). Not bad considering the 5.9L V-8. Once the weather changed this winter we noticed a severe decrease in gas mileage. We are now getting in the range of 9 - 10 miles to the gallon. Everything looks good and the vehicle continues to run great except for the mileage we are getting. If anyone out there has experienced this please post.
I can share one issue that has been corrected on our vehicle. On one of our trips, we had a problem with the transmission where it wouldn't shift properly. It ended up being a transmission fluid port for the torque converter that was too small. Once it was enlarged all transmission problems were solved.
 

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welcome to the boards
when is the last time you had a tune-up? I'd start there.
 

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You have to also remember that on many states, during the winter they switch to oxygenated gas, this gas is supposedly better for the environment during the winter months, but it is also has less energy potential approx. 5%, so that means it will also have 5% less gas mileage and 5% less power. So that is why your gas mileage may have gone down some. Good luck and God Bless. :biggthump
 
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Discussion Starter · #4 ·
That's a huge change in a short amount of time. Sounds like you're running too rich in your air/fuel ratio. Go to an exhaust shop and have them check your pre-cat front oxygen sensor to see if it's still within spec. They usually do it for free.

There's my best guess.
 
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