This is because i don't remove the sign of each nick (@,%,+) in the raw, but you can just add a $remove :
raw *:353:tokenize 32 $remove($4-,@,%,+) | write nicks.txt $*
on *:text:#channel:play "nicks.txt"
The play is better than the while in this case because by defaut, there are 1 second before mirc send each line.