Before i go out and buy new NGKs. Im going to take a wire brush to my old plugs because they have some brown crud on them.(NOOB Question) Is it ok to leave the plug holes exposed in almost sub zero temps overnight??

 

just clean off the old plug and thread them in there hand tight, or plug with rags, i would go with the first

 

Better safe than sorry - but if you're going with new plugs I wouldn't worry about cleaning the old ones.

 

Like the others have said, just stick 'em back in there. Takes 5 minutes most.

BTW, the brown stuff on the plugs is not a problem. Brown indicates a good burn of the air-fuel-oil mixture. What you don't want to see is dull or shiny black deposits, particularly on the center insulator (red area on the attached image). Dull black would suggest a very rich mixture or problems with your plug, coil, or other ignition system problem. Shiny black indicates an oil seal problem or simply excess oil in the mixture, or again, plug, coil or other ignition system problem.

 

Sub-zero temps will make absolutely no difference if the plugs are left out for a few days. It would only be an issue if you decided to powerwash the engine and got water inside the plug holes. I like to beadblast my plugs when I clean then. If you don't have a blast cabinet, Harbor Freight sells a spark plug cleaner that does the same thing for around 15 bucks. Well worth it for cleaning flooded plugs