Code:
on me:^*:part:#: {
  inc $+(%,partcount,$chan)
  .timer.unset.partcount. $+ $chan 1 5 unset $+(%,partcount,$chan)
  if ($($+(%,partcount,$chan),2) == 2) { msg $chan ffs you let them get away!! >:( }
}


* i replaced the timer name "2" with a real timer name, since using numbers is thundermentally wrong.
* i corrected the var used in the IF to be %partcount$chan

By only displaying on == 2 it well display once on second part in 5 seconds only.