Are using the block heater at all? we only been getting around -20 here. No problems starting though. Just the rough idling and loss of power.

BTW, wind chill doesn't affect the engine. If the thermometer reads -20, it doesn't matter how hard the wind is blowing, the engine is at -20. Just saying because a lot of people are referring to temperature with wind chill, when in fact it only affects living things.