Well, I suppose I should give a final update on this thread. haha.
After having the
BEM and CPU replaced, I stopped having the issues. The computers were simply too corroded from moisture and required replacing. All in all it cost me a few grand and I ended up spending nearly the cost of the car to fix it.
A little while after I got all of it sorted I started having serious engine issues. After taking a quick look at it, my heart broke and I gave up on the car. A few years later I ended up just selling it to a towing company that takes old cars. There was just so much to fix and I couldn't face it anymore. Nor afford it.
On top of that, I can't drive manuals cars anymore due to my left shoulder being ruined from work. The injury happened in 2016 and it'll never be the same again. Had to give up driving professionally and I struggle to drive my auto Corolla these days.
Here's to hoping your issue is a lot easier to fix than mine. And that you can continue to enjoy your manual V8 AU.