SCT Chip causes cold weather no-start

Beat my head against the wall for the last month trying to figure out why my winter DD 01 Zetec wagon wouldnt start when it got ~ below freezing.  No fuel or spark...  Replaced the fuel pump, rail pressure sensor, coil pack, fuel pump driver module, was just about to replace the entire ECU and key/cylinder/keys when I pulled the custom tune SCT chip completely.  Bingo.  Fired right up.  Granted it's one of SCT's old single bank red potted units, probably a good 5-6 years old...  But damn.  Had to drive my freakin blazer through this crap several times.  PISSED!