funny idlle

[Kurt McDowell <gmcd@domain.elided>]

      I've gott a good one for you guys. in my rewly rebuilt 345 w/
newly rebullt carb
Ive got a an intermintent funny idle. It surges then, almost dies,
surges, almost dies......
the cycle is about 1.5-2 seconds.
    however, It only happens somtimes, when it does, I have to run it
for about 15 minutes before
it goes away,
    somtimes, I start it up and it idles just fine.
I'm 100% sure the vacume is ok as i have a new carb, new lines, and all
new vacume-powered
diaphrams.
    I have checked the choke, but need to check it more thoughaly.
    I need to also check the heat riser, this is my next guess.
    Might be ambient temperature-related, needs to happen afew more
times before i can
confirm this.
    I am just hoping that someone has had the exact same problem and
knows what's up w/ my acout
and insights would be greatly appreciated. TIA
    Grant McDowell 76 scout 345