Weird thing happened

The other day, after i replaced the timing chain, i didnt get back to my original routine driving habits right away as a family member was in the hospital and i spent about a week running to and fro, but seemed to look like i was using more gas than before, but was hard to tell because of the diff. roads and places i was going, well back to original routine i discovered i was using twice as much gas as i used too. I 2 years driving the normal routine each day, it never took more than 1/4 tank per day, now it was taking 1/2 tanks per day!
I thought surely something has to be wrong with the car, so thinking back to the time it started, trying to determine what and when and all, the only major difference i could recall was, i started buying gas at a different place because of the recent price jumps.
So thinking it was worth a shot, i went back to my normal gas station with 1/4 tank in it and filled up, starting right then, fuel mileage was back to normal again!
Has been ever since, The car ran "ok" on the other, didnt notice any real performance difference with the "bad" gas, no missing or anything. But DAMN! how can gas be soooo bad it doubles its useage amount??? I have never had a car, or gas, to make that kind of difference in mileage before.
ANybody ever experience this with their Lumi?

JFYI- the bad gas was from a "LIBERTY" gas station. The gas i ususally use is from a SHEETZ store, both 87 octane.

Check the pump and see if the "bad gas" was ethanol mixed more than 10%. IF so, there is your mileage decrease. There is also a less volitile summer blend gas that reduces free vapor escaping when filling your tank that is used in smog prone areas that is crap too.

Check the pump and see if the "bad gas" was ethanol mixed more than 10%. IF so, there is your mileage decrease. There is also a less volitile summer blend gas that reduces free vapor escaping when filling your tank that is used in smog prone areas that is crap too.

Yes i used the blend once at Wlamart and it decreased mileage but not this much, i havent stopped back at the place i got the "bad gas" again so far. I also noticed something strange with them as far as pricing goes, i live and travel thru 3 small towns on my daily grind, each town has gas stations, Sheetz, 7 Eleven, etc, probably 3 or more in each, all of them lately have been bouncing up and down in price, except for where i got the horrible mileage gas, it has stayed constant at one price, sorta weird.

run the high octane for one tank as well as one of those bottled fuel injector cleaners you can get at any gas station or auto parts store (about 7 bucks) it will cost a little more but your injectors will be clean from the bad gas, which means better performance as well as better gas milage