As penguin mentioned, many auto parts stores will read codes for free.
I don't know what places you have in your location, but it's certainly worth a phone call to see if any of them will provide the service.
I hate to say it, but you really don't have much of a choice (get the code/s read).
We're basically at a loss to help you, until we find out what the computer says is wrong.
It could very well be bad gas, but if it were me I'd rather not guess.
Just in case...
Is it a reputable company where you bought the gas?
They didn't just get the tanks filled up did they?
I never buy gas from a station that has a tanker truck on the premises filling the tanks.
When they do so, it stirs up all sorts of crap from the bottom of the tank.
Best to move on to another station if that's the case.