Intermittent cold weather starting problem

Hello all,
I'm brand new here so I hope this is the right place to ask my question. It's not so simple so I apologize for being long on this.

I have a '92 Sentra SE 1.6 which is being an absolute headache & I believe it's only during the cold season that this happens. Sometimes it can be 30-40deg out & the car will crank & crank but never kick over, yet it can be 5deg out & it starts right up, although this is not always the case. Once after parking at a friends house on a 10deg day it was only 8hrs later I went to leave & for over an hour I cranked it but it would just not fire up (& had AAA tow it home the next day when it STILL wouldn't start), yet coming home after being away for 9 days with the car sitting frozen in the frigid cold driveway it kicked right over. Sometimes it'll be fine for 3 days straight but then leave it parked for anywhere from 4-16 hours throughout the day & it will just refuse to start, but leave it parked for a very short time, such as <1hr, it'll kick over almost every time. It's very unpredictable because when this happens, external conditions (outside temp, length of time parked, etc) are not always the same & it's driving me insane. On the times it DOES start, it'll drive forever w/o the slightest problem. But it's completely random & undeterminable as to when this problem happens which makes it completely unreliable to take anywhere now. I've even tried cycling the fuel pump with the key as much as 8 or 10 times before attempting to turn it over but that doesn't make a difference. You can 'feel' it wants very badly to start but just can't. It starts when it feels like it & that's it.
Notes -
1 - The fuel pump is OK. I hear it cycle properly for 4-5 seconds everytime I turn the key to 'on', before actually cranking.
2 - Every time w/o exception, regardless of successful or unsuccessful results, I always smell fuel as it cranks. And since it drives fine when it DOES start, I know I don't have a fuel delivery problem.
3 - The car has 120K miles & the problem only started last winter. It was fine all summer until 5 or 6 weeks ago. Other than this it's always been very dependable.
4 - Car has fresh plugs, air filter, & battery.
5 - I use the same gas every time.
6 - It's completely stock & never been tampered with (I'm the orig owner).
Thanks very much for the time on this. I hope I can repay the favor by helping someone else when needed.
Charlie
(Telnetter)

damn..seems like a complicated problem..have you checked in nissanforums.com? check it out,they can help..

Thanks for the tip NN. I'll check them out.