Where Did the Gospel of Luke Come From?

For the moment, it can be said that I think my argument that the Gospel of Luke as we have it is NOT Apostolic is unassailable, because the compiler says so in the first verses. This means that Theophilus is very likely the Bishop of Antioch, and NOT a rhetorical name for the general reader However, what has always struck me as odd is that this Gospel is IN FORM an epistle, and that means it belongs with the pastoral epistles attributed to Paul or to no-one, depending on the mss. The difficulty that remains is that Polycarp couldn’t have devised the wording, because the level of expression and imagination shown in it would have been beyond his abilities. So the CONTENT is Apostolic. But then where did he get it from? The same difficulty applies to the book of Acts. The quality of the first very powerful chapters is much higher than the rest of the book, which ranges from adequate to downright silly, with the absolute low points being the deaths of Ananias and Sapphira, and Paul’s miraculous flying hanky that performed miracles if Paul was too busy to turn up in person. The dividing line is just where what would have been ESSENTIAL knowledge and theological information stops, so presumably there was an OLD appendix to the Gospels that was concerned with the Apostles as a group, and then with Peter more than any other individual, and then the inferior part tacked on is about Paul, while the Twelve fade out. The theory of an original long Gospel having been cut up has a lot to recommend it. How could the Apostles have been so disorganised as not to attend to editing a final satisfactory book?