81-83 Service manual question

Thanks to all who responded to my "asterisk" question. I am learning quickly that continuing my relationship with the '83 will be mutually destructive without the help of a FSM (marital aid?) I am shopping around for one, and I have a couple of questions. I have an 83, so can I assume the 83 manual is the one to get, or do I need to get an 81 or 82 in addition to or instead of? I know that certain years used supplements that were of little value without the opening volume. I have also noticed that most of the manuals for the 81-83 years that I have seen are all "chassis, body and electrical" . The notable omission being "engine". I have heard that separate "engine performance" manuals were available, but I have yet to find one. I would assume that the engine manual would be crucial for any diagnosis or repair of the EFI system. Any ideas on where to find that one? As always, your input is greatly appreciated.