Calculate avg excluding the min and max times

[carlpier]

Hello,
I am looking for a way to calculate the avg excluding the occurrence with the time_min and time_max
Here is the simple base search:
index="nbdrest-performance" sourcetype="PerfNBDCustomTSV" | chart count min(ETms) max(ETms) avg(ETms) by Service | sort count | reverse
Any help would be greatly appreciated.
Thanks in advance!

[fdi01]

index="nbdrest-performance" sourcetype="PerfNBDCustomTSV" | chart avg count by Service | sort by count

or

index="nbdrest-performance" sourcetype="PerfNBDCustomTSV" | stats count avg by Service | sort by count