Had a guy with a F350 Powerstroke 7.3 pickup who kept bringing it in for lack of power when towing... He'd had it into like 10 different Ford dealerships because he traveled a lot...
We happened to be near a RV park he was staying at for a few months so they'd sent a rep from Ford out to look at this truck because none of the other shops could figure out WTF was wrong with it....
So after 3-4 days of this tech from Ford doing every possible test on it and not finding anything wrong, he finally asked the owner to bring the 5th wheel in with the truck... So the owner does and we took it down to scale it... The 5th wheel weighed 38K lbs... Now this was in 1997... That poor PS couldn't get out of it's own way trying to move that weight back then...