plug gap suggestions

what will i see running a larger plug gap? better idle and thorttle response and fuel mileage is what i have been told? I have a fairly rich idle mixture becfause of my carburetor having zero adjustability on the idle circuit, so i'm hoping this cd ignition and a larger plug gap will help burn my mixture better at idle. I sometimes foul plugs because of it, but i'm also running the stock 4 pin mopar ecu ignition, i indexed my spark plugs and that seemed to help with fouling the plugs. I just think the ignition i have is on a very fine line of being able to burn my mixture at an idle, everywhere else in the rpm range it does just fine, it only seems to struggle at an idle....