1999 Chevy S-10 Engine will not start when it gets cold

I have a 1999 chevy s10 that is a very dependable truck. During the Spring, Summer, and pre-Fall it starts up with not a problem of hesitation. When the temperature drops it will not even startup as you crack on it for more then 30 mins or so. Since it is a manual transmission you can roll it off a hill at our place and it will start up right away. I took a blow dryer and placed it on the coil pack from the bottom of the truck and let it run for about 5 mins with key turned on. It starts right up. I thought it was the coil pack and replaced it with a new one and still getting the same problem on not starting. Also, when I came home it has started to die and jerk and I try to restart it while in motion on the road with it in neutral. It sometimes hits and starts right up. It will not work when your in a gear trying to start it. This has happen about three times with many weeks apart traveled about 25 to 30 miles distance. They aren't no codes present or even when it dies during transit. Where should I put my focus at on this and how should I do it?