rx7 with idle problems

i am looking into buying a 1990 gxl. when at idle the rpms jump bak n forth from 1500 to 2000. i was wondering what other would look to first to find the problem. i was thinking it could b the o2 sensor being covered partially a clogged or a bad tps. anyone have any advice at all let me kno or if u have experienced this problem and fixed it or know of some1 who has.

what was the wather like outside? Did the problem go away once the car was driven for a bit before returning to idle?

yea it was kinda cold and it went away when the car was driven for like 15 minutes

what effect does the weather have anyways?

My car has idled high every time it's started when it's cold or hasn't been started for a while, but it usually lasts less than two minutes at most. Is this a common problem, or just a quirk?

its not a problem. its made that way