Short idle/engine Issue

[TealZR1]

My 91 on cold start is perfect. Idles down to 650 but always when reaching about 110 degrees it bogs down (runs rough) for about 20-30 seconds with rpm's decreasing some. After 20 seconds or so is comes back up to normal and drives perfect through normal operating temps. But again does this about every time. Had on scanner (ok) and no warning lights come up.
Thanks in advance of any help.