Chevrolet Repair: Bad Gasoline, chevy camaro, first tank

Question
Hello:

I have a 1996 Chevy Camaro.  3.4 V-6 Engine.  147,XXX miles.  I think I have some bad gasoline.  A week ago, I driven this car the entire week without any problems.  Friday night after work, I filled the tank for the following week.  I didn't drive this car the entire weekend.  It stayed parked in the garage.  I didn't go anywhere or even start it.  On Monday as I was out driving to my destination, the car started shaking as if it was going to cut out on me.  It drives really rough.  Prior to me filling my tank, the car drove fine.  I have had this car for almost 9 years, and it never have driving this badly.  Today, I drove it around, and it started backfiring.  I am still on that tank of gas.   I don't drive this car much, I have two cars.  
After driving the car for the week,  I refilled the tank, but at another station.  The car still drives bad, but not as bad as on the first tank of gas.  How long does it takes to actually drive out the bad gas?  Should I drive this car until the gas light comes on?  Is there anything I can pour into the gas?  Is driving my car under these conditions ruining my engine?  Like I stated before, I have two cars.  Since I have been having this problem, I  haven't been driving this car too much.  But I would like to start - to even out the mileage on both cars.

Bad gasoline you think??  

Answer
Hi Kevin,

That is a good possibility.  If you buy gas at the same time you see a gas truck in the parking lot, filling the undergound tanks, you can put dirt, debris, and other junk right into your tank.  That truck is stirring up everything from the bottom of the underground tanks.  Then you inadvertently put this into your tank.  After the truck is done, you should wait at least 1 hour before filling the tank.  

Another possibility is the presence of water in your tank.  This also could come from the gas station.  If their tanks got low, you could suck up crap from the bottom of their tanks.  

Third is cheap gas.  If their gas had additives that don't belong, you could have gotten 'hosed' this way also.  

What to Do???  

First and foremost is get the tank low.  If you don't think the car is running that bad, run the tank out.  If it is running horrible, then put in some dry gas.  This will eliminate any water in the gas.  Get this at Walmart, it is cheaper.  Then replace that with good gas.  Citgo, BP, Shell, Amaco are good places.  Sunoco, Speedway known to be bad gas.  

Once you have replaced the gas, change the fuel filter.  FOR SURE!!!  Then run some fuel injector cleaner through the system.  Use a good brand.  Get this at a good auto parts place, or try Walmart for price.  

This should fix the problem.  If not, write back.

Hope this helps.

C J S