i've got a 750cfm 4160 holley and when i go to take off from a stop it stumbles and will then suddenly take off if i keep my foot on the gas. this also happens if i'm cruising at a set speed and then give it gas. it's worst when the engine is cold and is almost non existent at full warm

 

Had the same problem awhile back and got..Accelerator pump circuit..pump cams,squirters,etc.That is the easiest place to start.I would go up in squirter size to start.