Engine Performance problem
2004 Ford Freestar 6 cyl Automatic 89,000 miles
About two weeks ago the engine light went on but, the car was running fine. We continued to use it and put medium grade fuel in it. The light shut off and ran fine. Today when you turn the key, it starts but intantly shuts down. Depressing the gas peddle to rev the engine does nothing. Any ideas? It was thinking the o2 sensor or the pvc valve? The other thought I had was the fuel injectors? Should we try an additive? Help us, Please.