you need to add the Populate list from array behavior to the body onload event as well to populate the child lists with the selections relating to ford.
your events should be:
1) set selected in list manufacturer = 1
2) Populate list from array, parent list manufacturer, child list model
3) Set Selected in list model = 3
4) Populate list from array, Parent list = model, Child list = engine
5) Set Selected in list engine = 2