98 Windstar Mileage

I have a 98 Windstar with the 3.8 (no antifreeze in the crankcase, thank goodness!) and 94K miles. The gas mileage has taken a nosedive of late -
overall mixed driving is returning less than 14 mpg. EPA estimates are 17 & 24 for this vehicle, and that's about what it used to get.
I just replace all six spark plugs & wires hoping that would help - put in OEM Motorcraft plugs, AZ wires - since it had been running less than smooth. It purrs like a kitten now, but mileage has not improved. I know that swapping plugs was a long shot, but figured it wouldn't hurt. My wife normally drives this, and I'm not sure how lead-footed she is. The tire pressure is good and I replaced that original steel wheels with aluminum last summer and I think they are lighter, though I may be mistaken. Otherwise, what else should I look for?
Thanks
G
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GMach3 wrote:

Get a scope on it and check the o2 sensor(oxygen sensor). I've seen it drop the mileage quickly....
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Hmmmmmmmmmmmmmmm. I'll do that. Thanks for the tip.
I mentioned to my mechanic (he gave me all kinds of grief for having Bosch Platinum plugs in the 3.8) and he told me he'd "Run a scope on it" -- the favorite answer!
Maybe he's on to something. Perhaps that's why he's been in business for 40 years. :)

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98 Windstar GL 216K 90% highway driving..Averaging 22.3 MPG

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