Gas Milage went South on 98 STS

The mileage I am getting is 14 mpg in the city, hwy about 18. It used to be at least 5 to 6 mpg higher. The car has not had an engine tune up for over
100,000 miles. Could this be the problem, the mileage just went south so quickly? I have 168,000 miles on car. The car does not miss or sputter, its just sucking up a lot of gas. Any suggestions?
TIA Terry snipped-for-privacy@pacifier.com
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"The car has not had an engine tune up for over 100,000 miles."
Don 2001 Deville DHS built by Yugo.

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wrote:

I would check the air cleaner - could be that simple.
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