Originally Posted by Spooler

If your issue is only at idle you need to look at the radiator fans. Make sure they are kicking up to high speed at idle and they are both working. You could test these with Nissans Consult. Not sure how you would do it without the Consult tool. Uprev or Ecutek may be able to do it.

I am going to ask a silly question. Did you remove the bleed screw out of the radiator when filling with antifreeze?