Yes cars get lower MPG in the winter due to warm up and cold air, but not by that much.
I'd start with a new air filter, and if that doesn't do the trick, new plugs, maybe new wires, and a fuel fiter change.
K&N is also an improvement over a stock air filter, moves more air
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Me
2000 Alero running 14's
2005 Nissan Altima (her's)
1967 Olds 330 motor sitting on a stand
1985 Delta 88 w/1968 350 rocket ( MURDERED )
