I just had quite a bit of work done on my 2003 Alero. I had the manifold gasket, egr valve, and thermostat replaced along with a tune up and new bearings in the front (which I am sure is not related). The check engine light came on less than 24 hours later and there is a stronge smell of gas and my mileage has tanked. Any thoughts? I'm just a poor girl trying to get educated....

 

It sounds like you have a leaking fuel injector. If you turn the key to on but do not start the car, you may be able to see where the fuel is leaking from. In any case, driving with a fuel leak is dangerous. I would have the shop that did the work fix the leak, it sounds like they caused the problem.