1996 Buick Century temperature gauge not working properly

[quote:7958658fad="cardriver2222"]Other Category problem
1996 Buick Century 6 cyl Front Wheel Drive Automatic 134000 miles
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ive replaced the thermostat and the sending unit....so ive probably got a bad gauge. The thing is though i get poor gas mileage like it never warms up. the gauge only goes up to the 1/8 mark and it takes awhile to get there. i drove 150 miles highway at 55mph and grandma take offs n only got 20 mpg...did i get a bad thermostat or is something else wrong...no check engine light though[/quote:7958658fad]
do you have a check engine light on?
hook it to a scanner and read data