idle and oil temp Question

[icebergc90]

I have a 1989 nissan 240 sr20det. The past couple of days when i start it in the extreme cold (10-15 Degrees) the idle has been surging really bad. It will be at 2000rpms then drop down to 1500rpm for a half a second. its stops after about 2 minutes of driving so im not too worried about it, is it pretty common for this to happen in this weather? also when i am driving the oil temp will go all the way up for 10 seconds then return to normal, this happens about every 5 minutes. Any ideas what is going on with it?-Thanks