2002 Pontiac Grand Am- won't start

I have a 2002 Pontiac Grand Am with a 2.2 liter 4 cyl engine and approx. 30000 miles. Its also an auto transmission, and front wheel drive. I had been having problems with my car starting. I had a mechanic come and look at it, and he got it started. I got my fuel filter replaced, an oil change and had the entire fuel system cleaned. My fuel pump is also good, I get the sound of it starting up when I turn the key on. A couple weeks later, same thing, won't start. I had the same mechanic look at it. I've tried replacing the ignition coil and the ignition control module. Neither worked. The power cord to the control module is getting power, but there is no spark when we try to start the car. The spark plugs are also good. I was told it could be the camshaft sensor, but I have no idea where that is located in the engine. Please help!