When it is really cold out, I'm talking anywheres from minus 23 to 30 celcius, the car will start, run at 1500 rpm for a minute or two, then die. Runs smooth, and dies. Will not restart. Already unplugged the cam sensor with no result. The car also misfires once very randomly when I am on the road, but not often.
To get it going this morning, I used a heat gun arounds the crank sensor and harness for a few minutes, and it fired right up.

A month or two ago, it misfired 3 times, causing the car to lurch bad, and did die on the highway, and the tach went to zero. But as soon as it did this, it fired right back up. I got a SES light, with a code 18, which is a cam/crank error.

New crank sensor, used ignition module so far, but they were for no starts long time ago when it was summer. Other than that, the motor runs like new. Car has 415,000 kms on it, and the motor is from a my old 91 lesabre with arounds 180,000 kms.

I'm a mechanic, but this has me stumped, and I hate replacing stuff that isn't broke! Haha! Will do if "I have to, but why only when it is very cold out?? I used to commute 2 hours a day in minus 35 to 40 weather, not even plugging it in, no problem starting when other cars would not!
Any ideas would be a help!

If my info is wrong below, I haven't been here for a long time, and this forum has changed! Here is updated info.

1993 Buick Park Avenue, 3800 Vin L. Gran touring suspension. No mods, its all stock!