Fuel Problems

My car idles really low and dies on me frequently but can give it gas and it will stay running. I've had it put on diagnostics and the computer said it was the ERG, I replaced it, same problem occurred. I replaced the fuel filter, same problem. I've not replaced the fuel pump. Could it be the fuel pump or the fuel pump relay? Why does it keep dying? After the car sits all night the following day when started the car smokes for a min then clears up. Smoke is light in color and looks kinda blue.