@Popee You say the car runs well. Does it idle smooth once warm? Is the engine responsive and smooth under load?
Is it just the cold start that is a problem?
If so, it may be that you just need to figure out what the car wants when it's cold.
I have an example for you(and this is NOT a reflection on you!).
I have a customer with a sand rail, 1835cc with dual 35mm Solexes(that I installed and tuned). The carbs have electric chokes and it runs and starts well from cold.
However, he came out to visit me one day, and had trouble starting the car when it was warm. The car had sat for about 15 minutes. He simply turned the key for a LONG time until it caught.
Now, me, I've had carbs all my life, but he had ALL injected cars. All he needed to do was VERY slightly crack the throttle as he turned the key. Instant start, let off the gas, perfect idle.
There was nothing wrong, just needed to give the car what it needed. Now he has no trouble at all, anytime.
As I said above, maybe you just have to experiment and figure out what the car wants when it's cold. They can be cantankerous and difficult when cold.