Hard to start engine
 

Is there any mechanic on this forum can help me diagnosed the problem

That is a loaded question. You are going to have to provide some more detail beyond just ‘hard to start’.

Where in Canada are you? If near Winnipeg, hell, I’ll take a look at it.

hard to start
 

I live in Montreal Canada,
Could it be a problem with the starter because I have a friend who owns a 911 and he had a similar problem 2 years ago and the real problem was with the starter he replace the battery and other component before the starter and finnaly after replacing the starter he never had any problem to start the car evn when the engine was warm

It could be countless things. You need to provide more information as to what the issue is, what the car is doing or not doing.

There is simply just not enough information to provide you any assistance.