Hyundai Repair: Cold weather starting issues, coolant temperature sensor, fuel pressure gauge

Question
I have a 00 Elantra with roughly 75k, 5 speed manual. As winter approaches I am worried about a reoccurring problem I have had the past two winters.
Problem: If the car sits outside in temps below freezing for more than 5-8 hours its very difficult to start. Cranks fine, but takes several minutes to fire. No problems in warm weather or on cold weather restart if less than timeframe listed above. A local mechanic suggested the cold engine sensor... I cant find any such device in my Hayes manual. Filters, wires and plugs have all been replaced. General performance not what she used to be, hesitation in low power band.

Thanks for reading.

Answer
I'd primarily suspect the coolant temperature sensor (probably what the local mechanic meant) or perhaps the fuel pressure bleeding off.  If the problem returns, you might try installing a fuel pressure gauge on the vehicle, starting it and turing it off.  The fuel pressure should hold at 10psi or greater indefinitely after you turn the car off.  If it doesn't, your excessive cranking time is necessary to build up sufficient fuel pressure.