When I was doing automotive diagnostics and had a vehicle that I had trouble figuring out, knowing good and well that I had done every test, in the correct sequence, at the prescribed temperature, by the book, etc., consulted with the other mechanics on the floor, ran all possibilities past the service manager, and still could not come up with a solution I did one thing that (except for one time) worked perfectly.
I put everything back the way it was and started from the begining. By the book, no skipped steps, no shortcuts, no 'Eh, I already checked that three times', etc.
From point A to point Z, in order, by the book.
If that doesn't work then do like I did and throw a 13/16" combo wrench acrost the shop and shout an expletive loud enough that the whole shop can hear...... Well, on second thought, don't do like I did. Have someone else look at it. Sometimes we just cant see the trees because we have been stairing at the forest too long.
That one I couldnt figure out.... The Matco Tool man walked over, picked up my wrench, politely handed it back and asked what the problem was. I told him everything I tried. He then picked up the same wrench. Tapped the mass airflow sensor and the damn thing hickupped. Tapped it again. Hiccup. Problem solved.