Go out walking

Good evening to all of the forum I have a doubt I have a golf mi 99, it has been going out in the morning, but this does it, it does not do it when it is heating goes out two or three times and if I try to start taking advantage of the impulse that takes the first time it does not want and I have to go 2 or 3 times so that it starts and after 2 or 3 minutes It is not going off, but nothing else does it to me in the morning because the rest of the day it is very well already changed the gasoline pump, the cables and even the distributor's lid they already checked the coil to see if it was starry or something like that but it is fine to scan it and do not send any code. What could be?

Czech the boot sheet in some models gives the can, if you leave it in a static rementi stops or running for a long time