I'm not tryin to say "I told you so" but there is plenty of this kind of problem out there. One way I used to create braid shield.........and you can buy shield separate.........is to carefully strip the outer jacket of some coax cable. Not TV cable, usually, but CB/ radio feedline, RG-58/ 59, RG-8 etc. You can "bunch" the braid up by pushing it to make it larger to thread the wire, then smooth / stretch it out.
Yes you are correct. We used a piece of braided steel covering on my buddy Larry's 1988 D150 (see the T for 2 thread). We had one heck of a time with RPM noise with both of the systems. Larry's set every code in the book.
There was on guy had an MSD interfere with a Mopar voltage regulator. Stuff like MSD is particularly troublesome because there is so much power there