If you really think you got a load of contaminated gas, notify the station owner and hold on to the receipt in case there's any damage. We've had instances around here in the past few years where people's car engines and fuel systems were screwed up by water or other contaminants in the fuel. In one rather infamous case it turned out the cheapskate station owner had bought a load of "reclaimed" gasoline from some folks who went to junk yards and drained fuel tanks.
Anyhow, if you really think it's bad fuel, don't screw around throwing additives in the tank, get a simple syphon and syphon it out and put it in a big gas can. Fill up with fresh fuel from a known good source and see if that fixes your problem. If it does, take the crappy gas over to the place you bought it and invite the station owner to refund your money. Offer to pour the bad gas into his car.
Jerry