While I'm really glad my stuff gets used, it's not the best solution in this case..
var %fixit = $calc($ctime(%newtime) - $ctime(%oldinfo))
Now %fixit should contain the number of seconds that passed between those timestamps and you now just have to get the biggest number. That's going through the entire list checking each entry and keeping both the largest number yet and the item name where it was. To actually display the duration, either do the $datediff at that time if you can find both timestamps back, or add the $datediff after the number of seconds in %fixit and then use $gettok to get either the number of seconds or the human-readable format...
