well, since you've done so much work yourself already it might eb a stupid quesiton to ask, but have you cleaned the AFM?
or have you re-soldered the AFM joints inside the actual AFM?
search for AFM+SOLDER to see what I mean.
Also, iridium plugs don't mean that you don't have a spark issue.
how old are they?
what gap?
what heat range?
and since you have been "tuning" and telling me just above that it has been so rich it BURNS your rear bar etc, those plugs will be well f**ked by now.
Fixxer is correct.
$24 for 6 new NGK BCPR6ES – 8 plugs already gapped to 0.8mm may fix your problem... well.. one of them.
lol.. mate it's your car and your choice... but from all your money saving, it looks like it's going to cost you in the end.