Select > Same > Fill Color does not work for you?
My mistake: i selected it within a group. When i select the line out side a group, it select all lines with the same color in all groups. all is good.
but now comes the next problem: for some reason it select line with another color (btw those line used to be purple but i changed them to green)
It goes very fast, but as far as I can see you select all objects with a fill of none.
That can result in many different stroke colors selected.
You are right! thanks! i should have click on "Fill & Stroke"!