No, it is not true that most NT scholars think most of Acts is fiction. There are two basic approaches to the book among most NT scholars: those who think it is not accurate and those who place Luke at a level with other ancient historians (ie largely accurate). I actually think most are in the latter category. My commentary does work through this a point at a time, arguing for the quality of Luke's work, as well as arguing for a date and authorship in the 60's or at the latest in the 80's.