I haven't time to read all , so sorry if it's on here.

Mine died on the highway and I got the dead ECU code. I swapped in my spare ECU and got dead code.
I noticed the location of the MPI relay , without the plastic cover, and thought Hummm,,,
I took the cover off and one of the 2 electromagnet relay switches was green with corosion. I replaced it wirth the relay from a 3.0 Sonata and it was good as new.
In a humid or snowy habitat I would check it out.

dave h.
'89 Raider V6 5spd;Aisin Hubs;; Gen2 LS: frt. brakes, rear coils;U.C.arms;R.trailing arms;idler arm; rear LSD axle w.disc brakes ;2 battery system for Dog's fan; relocated ECU; custom bumpers;J.Baker receiver;Conferr roofrack; t-bar crank.