I have a 2004 Caravan. 2 days ago, the engine started to sputter while in idle and taking off from a stop. It has gotten cold in the evenings so I thought maybe it was moisture in the tank. I added gasline anti-freeze yesterday to displace moisture and it actually got worse. Shortly after adding the fuel additive, the engine light came on, and the sputtering got worse to where if I accelerate hard, it sounds like it backfires down at the manifold. ANY IDEAS!?

I just tried the "key -on/off thing" and the "engine" light flashes 10 times. What kind of code is that?
someone please help.
thanks