Cold no Start cm870

[Shinaver]

Hello to all,
I have owned this 2007 international 9900ix for 4 years with a cm870 current mileage 1.2
million. No rebuild or engine work has been performed during those years.
So let me set this up. During the winter months when the truck is plugged in there is no
problem with start up at all no matter the the temp. Now the ugly side. When the outside
temp
is at or below 32 degrees the truck will not start without aid like ether.
Took it to the local garage that i have been doing business with for 4 years. The computer
showed inaccurate ambient temp,they replaced the intake air sensor and sent it out the
door.
Next morning approx. 30 degrees outside not plugged in, truck would not start without aid.
The shop says without throwing parts and money at it, they don't know what is the matter.
So i need to know how does warming the coolant in the engine change how the engine will
start at those temps.
The shop said that fuel pressure is good, no leaks in system, no codes present until after
trying to start when not plugged in, and then the codes relate to cranking time.
Please feel free to ask questions, i have tried to find the anwser in the forum without any
luck.