Force

I have a stock 98 SS and when I start it on a cold day the idle sits at around 1300rpm. I can drive for close to an hour to warm the car up but when stopped the car still idles high. If I turn the car off for 5-10 seconds then start it up again the idle goes down to normal. I am throwing no codes. Any ideas? I was thinking vac leaks but why would it go away after the restart when warm?

Thanks

99Z2ate

I think that's pretty normal