Well old "method" no longer works with vanilla game, but you may just change {1 Down 1 UP} to {1} to revert to it.
You may also try adding one of
SetKeyDelay, 10, 10
SetKeyDelay, 50, 50
SetKeyDelay, 0, 10
SetKeyDelay, -1, 0
as the first line in script and try it with both new and old method to see if it helps.
This problem is likely caused by ISBoxer as if you just open 2 game clients without it you'll most likely see it keep drinking pots.