stalling when driven

whenI start my Durango it does fine, runs smooth. I drive it where I am going and when I come back and start it, when I go to take off it acts like it isn't getting any gas. It sputters and then finally takes hold and goes. usually when it goes it runs ok from then on, until it is cut off restarted, and I drive again. We have replaces the idle control sensor, the map sensor, and bought an oxygen sensor. We haven't put on oxygen sensor yet because we cant get the old one loose to remove.