Perfect Chevrolet does not start in cold

Hello, everyone.
My Chevy, a venture of the year 2000, works perfectly, does not pull, has a powerful and immediate acceleration, very striking softness and smoke is not appreciated by the escape or strange noise of the engine.
The problem that presents me for a month is as follows:
in the morning the car takes a long time to start. I have to try between 6 or 8 times to start, and when it starts it maintains an irregular rating for about 4 to 5 seconds, past which is fixed in the thousand laps and thus remains constant.
Once the car has started, I can stop it for an hour, two hours, three hours, five hours that when you give the car the car starts the first and with the perfect idle from the first moment. Only the Proper not starting is presented again if the engine remains more than 10 hours in a row.
I took him to the workshop and put him:
- New spark plugs.
- New spark plug cables.
- Fuel antiretrocetic valve.
- New fuel pressure regulator.
And the car was still the same. Seeing that the mechanic did not know where to put a hand in the car, I took it to Bosch Service and plugged the tester into the car, detected failure in the temperature sensor and the vapor sensor of the fuel tank.
They have now put him:
- New temperature sensor.
And the fact is that the car now starts much better. I explain: if I needed six or eight attempts before to start it, now it always starts the second attempt. To the first attempt he does as he wants, but he does not start, the second starts perfectly, and so on the whole day until the engine is left for more than 10 hours in a row.
Obviously the failure has improved very markedly, but does not start the first.
Another thing I have noticed is that the more environmental heat it does, the better the car starts.
I want to insist that once running, the car is extremely silent, soft in the march, very vigorous and fast reaction when stepping on the accelerator, never pulls, the idle remains stable, and can be left parked for less than 10 hours (approximately) that always starts the first.
What possible causes and solutions do you find with these symptoms?