distributer cap mods?

no water in oil or oil in water, this engine doesnt even have 20 thousand miles on it. It has a brand new fel-pro intake manifold gasket, i used al brand new bolts and washers and torqued the intake down.I have steady vaccum at idle with my vaccum gauage, before when i had the vaccum leak on intake my vaccum was un-stable at idle.
This is something else, and i'm starting to think its fuel not ignition, If i first fire the engine up there is no miss at all, and i can let it idle for 20 to 25 minutes with no miss while at an idle, then i go drive it around and let it idle after driving and the miss is there, Also it is extremely cold here where i am, doesnt cold wether lean the carburetor mixtures out? I'm thinking this cold wether wich is 5 to 10 below zero has my mixture too lean at idle. My plugs are not fouling like they did when i had the intake manifold leak ether, so the steady vaccum at idle and not fouling plugs makes me think its something other then a vaccum leak at the intake manifold.
And when i put this new intake manifold gasket on a month or so ago, i sanded and cleaned the heads and the intake and i used the edelbrock gasgacinch sticky stuff thats supposed to help form an even better seal. I'd just be very suprised if it was a vaccum leak at this point, plus yesterday i sprayed wd-40 all along the intake and listenend for change in idle and didnt hear one.
Right now i am running a 600cfm manual choke edelbrock performer carburetor and i have .092 jets in the main circuit and .092 jets in the secondary circuit and i am running the 7047 metering rods with the silver step up springs, I was told maybe a one size smaller metering rod might help this situation? because the fuel at idle goes past the metering rods and down the jets correct?