2004 Dodge Dakota starting problem

I have a 2004 Dodge Dakota with a V8-4.7magnum. I now have 46,000 km, but my problem started at 11,000km. When I start the truck it spits and sputters and then stalls. I try a second time and the same thing. I then have to hold the gas pedal to the floor to clear flood it to get it started. This does not happen all the time but only seems to happen in the winter when it is cold. Currently the problem is getting worse. :Cry: The dealership says they cannot find the problem. I gave the truck a tune up but that did not work. We changed the fuel pump thinking that was the problem and the next day it did it again. I sure hope someone has an answer to steer me in the right direction. All replys would be greatly appreciated. Thanxs.