That "same adhesive for both jobs" shortcut is the same one that gets people every time, like using one tool for two totally different tasks just because it saves a trip to the truck. Heat and moisture move through a slab in ways you can't see, so the glue that grabs tack strip fine can still break down under carpet that's flexing all day. Bite the bullet on the moisture test, it's way cheaper than eating a second install six months later.

Man, come on, two hours of guessing has never once made me run out and drop 350 bucks on a scanner. A phantom misfire on a Ford is like the most normal thing in the world, could be plugs, coils, a dirty injector, vacuum leak, you name it. You could've swapped a coil pack around and watched the misfire move for basically free instead of throwing parts darts. I'm not saying bi-directional tools are useless, but a $20 noid light or a compression gauge would've told you a lot too. Everybody on these forums acts like the second you get a real scanner you turn into some master tech, and that's just not how it works. Feels like you wanted the tool anyway and the F-150 just gave you an excuse.