New parts now are terrible. Looks like you are really getting into this troubleshooting on the older systems, and since your grandson has one also, I recommend you buy this book. It's where I got the testing info from, I am not that smart and do not want to portray myself as being than smart either. This is a good book.
How to Tune and Modify Ford Fuel Injection [Watson, Ben] on Amazon.com. *FREE* shipping on qualifying offers. How to Tune and Modify Ford Fuel Injection
www.amazon.com
They sell another with the same name but a different picture on the cover. Not sure if it's the same with updates or not, so I made sure to link to the one I have.