Back fire, sputter, surging, dies at any speed, just shuts off.

One day it will drive just fine. Next it will sputter and surge. Then drive thru town at lights it will die if not on the gas/ sometimes. Then chugs and surges going down the rd at 30mph. Some times it just stops having problems for a couple days. Just runs great. (Alt, plugs, wires, battery, cap, rotor, gas cap, water pump, valve cover gasket, all new, installed by trusted wrench.)