Hey dude,

If it does turn out to be your ECU, I've got a spare for a '90 you can have for like $20 + shipping. It's just sitting in my garage collecting dust.

1989 Mitsubishi Montero SWB V6, Aisin manual hubs, gen 2 front brakes/rotors, rear LSD, A44DL lock-up transmission, BFG 33's.