Ok, since Dave E was asking, I dug through all my books and found what I think is the best possible book to learn almost anything you need to know about PID loops.
This book was written by a former DuPont Engineer back in 1990 and was self published and it still available from his web site today for $25.
I used this book to solve many problems and if you’re not a PID engineer, and you need to work with PIDs in any form, you really do need this book.
Here is the web site: http://straightlinecontrol.com/