Truck isn't idling right like its thirsting for gas and stalls when i come to a stop.

i thought it maybe had water in the gas but i replaced the fuel pump and put dry gas and lucas in it. it idles like it's thirsting for gas(the gas tank is full or half full when it does) it runs good when i go down the highway and when i drive on the road, but when i come to a stop most of the times it stalls it starts right back up though. I turn it on and let it idle for about 15 minutes and the idling gets better and doesnt sound like its thirsting for gas as much.