Just reading the initial post, I would first find another mechanic...

...but that may not be possible.

So...you said that it starts and runs great in warm weather which would
tend to rule out the fuel delivery system...fuel pressure, regulator, fuel
filter, fuel pump, etc.
The Temp II sensor seems to be the obvious suspect, but not knowing what
the mechanic did/checked, I wouldn't want to junp to that conclusion.  For
example, how did he determine the fuel pump is good? Pressure test?  Did
he check to see if pressure dropped after shutting off the pump?, etc...

Pat

From:   OlRivrRat <OlRivrRat@COMCAST.NET>
To:     vanagon@GERRY.VANAGON.COM
Date:   11/17/2015 09:00 AM
Subject:        Re: crank, wont start
Sent by:        Vanagon Mailing List <vanagon@gerry.vanagon.com>

        What Vehicle/Year/Eng' are we WorkingOn here ~

On 17 Nov , 2015, at 8:58 AM, Stan Shapiro wrote:

> I am in Sedona AZ, warm days, and recently very cold night into the low
30s.
> When the van is warm, it starts and runs great-perfectly normal!!   In
the
> morning, when it is cold, it cranks but wont start.   Not even a hint of
> getting close to starting.
>
>
>
> I have taken it to the local mechanic here in Sedona twice.  It is
currently
> in their lot.   They are lost as to what to do next.   Good Spark, new
fuel
> filter, fuel pump is good.    Runs great all day, wont start in the
morning.
> I don't think they have checked the Temp ll sensor-I will check with
them
> again this morning.
>
>
>
> Does it sound like it could be a temp ll sensor issue?   Can I check the
> resistance of the sensor when it is cold-I am guessing it will be high
if it
> is not functioning??
>
>
>
> stan