i have a 94 buick skylark with a 3100 engine and the gas milage sucks i fill it up and go through a tank in about three trips to town i gave it a tune up with a new gas and air filter and plugs and wires the only thing i haven't changed is the injectors and the o2 sensor i have flushed out the injectors and it runs smooth with plenty of power. what usually goes wrong with these cars and what front end body parts will interchange these cars are hard to find in the wrecking yards around here.

How many miles are you getting in town on a full tank?

18 city/26 hwy/ 21 combined...on a new car...

Fill your car up.....reset odometer....drive about 200 miles.....fill car up again, and divide miles on odometer by amount of fuel on second fill up....

Agreed that you need to get the actual MPG numbers to figure out how far off your mileage is. "Going through a tank in three trips to town" doesn't mean much in a quantitative way.

usually i get about 250 on a tank of gas

Next couple tanks, use your trip odometer (reset to 0 when you fill up) so you know exactly how many miles you've driven before the next fill up. Divide number of miles by the number of gallons it takes. Do that a few times for a good average of MPG'*, then let us know what your numbers are looking like.