3.1 chevy hesitation

i have a 95 Chevy Corsica 3.1 with hesitation when taking off from a stop.it only happens when you start the car and go. after you get going its good until you let it sit . if you start the car and let it idle for a minute it runs good. i changed the map, temp, and knock sensor.sometimes it will stall when you are going slow in a parking lot it will stall when motor is cold