I have a 2003 dodge ram 1500 4.7l v8.....and my engine light comes on then my trucks starts lacking power and goes put put and dies. I start it up and it runs rough, and when i give it gas it wants to

Rather than to point out the obvious - you get what you pay for - let me try to help. Vehicles in the scrap yard may sit there anywhere from 1 to 12 months or more, depending upon how part-worthy they are. They get crushed when they are no longer worth the space they take up. Add to the fact that the vehicle may have sat at the owner's home for years before being sent to the yard, and you have no idea how old the gas is that you put in the tank of your Dodge. Fuel tanks will condensate over long periods of time, and there was probably a good bit of water in the gas you obtained. There could also be rust and dirt from inside the tanks as well. And certainly hope that the scrap yard did not mix diesel fuel with the gasoline (it happens!)... That said, the white smoke you mention is a giveaway of water in the combustion chamber. Normally, I would say use dry gas, fill the tank, and drive the water away, but this seems like much more than trace amounts of water. My recommendation would be to have a fuel sample taken from the fuel rail (about a quart) and checked for water. If there is substantial water (I as believe), then you will need to have the tank drained, the fuel filter replaced, and the injectors and fuel lines purged. And next time, pass on the free gas!