Idle miss

Hey guys, i got a 91 chev k3500 with a 350, cold air intake tb spacer. i just threw new iridiums into it with some ngk wires as well. when ever its colder like 0 degrees C and below itll have a slight miss and wont go up to high idle right away (so i usually help it out). I was at an ngk seminar a while ago and they said if u put alot of miles on, tow a load, have headers, cold air intake or performance chip go one plug cooler than stop (which i did) but coming into the winter (here in canada) it seems to miss at slightly higher temps. could this be becasue of the plugs, anything else i should look at? (at colder temps like -20 to -35 celsius itll sometimes die right away on start up too)

Here in Wisconsin we can get down to -35 f and the last thing you want is a cold air intake. Put your old air cleaner back on and put the correct plug heat range in.