Seems like most good advice sounds wrong until life proves it right.

Read a forum post years ago about a guy with a similar issue, but his was from the pump itself working loose over time. Those old mounting flanges can get brittle with age and heat cycles, especially if someone overtightened the bolts during a past repair. Makes sense it would cause a rough idle with an air leak in the fuel system like that. Surprised it made it all the way from Boise before it got really bad. Always something new with those trucks, even on a motor you think you know inside and out.

Try a mat with a lip to contain spills too.

I always assumed shoddy work was just laziness or lack of skill. Reading about that specific tape pattern being a known trick to fail inspection completely shifted my view. It shows a deliberate choice to cut corners that gets buried inside the walls. Now I wonder what else in my own house was done with that kind of intent.

Watch how tiny bits of life collect in pockets and corners until they become a problem. My entire house works like that, just a slow build up of receipts and loose change in every junk drawer. Your rock collection just upgraded to a geological event.