Strange Fuel Starvation when its Cold Outside

[paladintrucks]

Morning from the US
I am a long time Safari/Patrol Owner, Ive had 5 or 6 over the years. I'm an importer in the US.
My current daily driver is a rare beast, Its a 94 Safari AD (UN Spec) NA TD42 24volt Automatic with 7,000 kms, No, seriously it has 7,000 kms.
I bought it 6 months ago, it was apparently a never delivered UN vehicle. It was driven 15kms a month and serviced every 6 months.
It is literally new in the wrapper.
Imported it a few months ago, had an ODD giant diesel particulate filter underneath about twice the size of a muffler. Pulled that!
Here is my problem, it starts fantastic no matter what them outside temp, glow plugs work a charm. Runs beautifully.
When the outside temp nears freezing it still starts beautifully but after 2 or 3 minutes it want to DIE.
If it just sitting running it will gradually start to drop rms from 900 to stall like it is running out of fuel, then a very hard restart. then feels like its running on 4 or 5 cylinders until it clears its throat.
If I am driving it after start it runs fine, but if i let off the throttle even at 60kms it will drop rpm's and die. If I come to a stop, same thing.
It takes reaching full operating temperature before it will stop acting this way.

Facts
Replaced fuel filter and checked all plastic lines
Only happens when its cold outside, near or below freezing
Its done this since I got it 3 months ago at 5,500 kms
We have installed the DTS Turbo system, made no difference
I have run fuel treatment in it every fill up
Does not matter the orientation of how I park it, uphill downhill all the same
Runs absolutely beautifully and strong as an ox UNLESS I come to stop or completely lift off throttle
Once fully warmed up it has ZERO symptoms.
I have another 96 Safari with factory Turbo TD42 and his has never exhibited any similar symptoms

Any insight would be GREATLY appreciated, i'm at wits end.

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