I don't know if anyone is still reading this, but for my own mental well being I am posting an update anyway. I just got my car back from the dealership and it made it 4.4 miles before the "Check engine" light came on again. The dealership thought that they had the problem when they discovered that the gas cap was bad...obviously this was not the case. Here are the facts as I now understand them...appearantly the last dealership didnt think it was odd to change the same part every two weeks.

The tech at the dealer has now replaced a fuel system purge valve, explained to me as the part that releases the pressure from the fuel system, three times now. They have no idea what the problem is, but I am hoping someone out there may have heard of this and be able to point me in the right direction.

Thanks again all for the comments so far, I have been passing them along to the tech at the newdealership and making sure that they tell me what is going on this time.