Try
#!/bin/sh
/usr/local/bin/wrun 'uptime;ps -elf|grep httpd|wc -l;free -m;mpstat' &
pid=$!
sleep 5
kill $pid 2>/dev/null && echo "Killed command on time out"
UPDATE:
A working example (no special commands)
#!/bin/sh
set +x
ping -i 1 google.de &
pid=$!
echo $pid
sleep 5
echo $pid
kill $pid 2>/dev/null && echo "Killed command on time out"