Excessive gas usage on 1993 Buick LeSabre

High idle on interstate, idle corrects after restart.

Asked by for the 1993 Buick LeSabre
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Lost of things can contribute to poor fuel economy. Ensure your car has had basic maintenance (spark plugs, fuel filter and air filter). The oxygen sensor coolant temperature switch and air flow entering the engine are the three key inputs the computer in your car uses to trim and adjust the fuel mixture.