NoPistons -Mazda Rx7 & Rx8 Rotary Forum - Strange Issue, Seems like ignition breakup?

Hi everyone! First post here, sadly it's about an issue that's been plaguing me (and my car) since last year. Hoping someone can help me out to get it back up and running proper so I can get it retuned for more power!

If this may seem like a topic that's been covered in another thread, please post a link. Spare me the "search n00b" BS. I was/am a long time member of honda-tech (yeah yeah i know, :jerkit:) so i've been through the whole thing of watching people spend time telling people to "search" just to bump their post count up instead of being a helpful member of the community.

Here comes the read....

OK, this is going to be long so bare with me. I need some help on what else i can look for to help solve my issue with what seems to be ignition breakup under boost. Good opportunity for you problem solvers out there!!!

The car: 1994 RX-7. Street ported and single turbo converted with a twin scroll t4 62-1. 550cc Primaries, 1600cc secondaries and a 255lph fuel pump. Stock OMP still in place with stainless lines. Apexi PowerFC with Datalogit.

The problem: At the end of last summer, the car ran great. No issues what so ever, would carry 17psi of boost through the RPM range no problem. I decided in October or so to change my spark plugs as a routine maintenance item. Immediately after changing my spark plugs, as I was taking it back to my garage i decided to do a pull to see how it felt with the new plugs. That's when it first broke up while approaching full boost.

I haven't gotten a chance to drive it much, let alone even work on it but now i've got some time to look into the problem. I retraced my steps, swapped the plugs again just to make sure there wasn't one with cracked ceramic or anything. This time i went with all heat range 9 in both leading and trailing. Took it for a test drive, problem still there.

I dug deeper, realized i was not registering any knock reading. Traced the knock sensor wires and found that the plug for the knock sensor was just resting inside the connector on the harness, but was not clasped. I thought for sure I had found the issue. So i corrected the wiring. NOPE. Problem persists still.

Next step is finally did some logging. There are some things perhaps I don't fully understand about the ignition split, so maybe this is normal, but at part throttle my IGL reading is 22~23 while IGT is 11~13. However, when at peak throttle (4.8v) IGL drops to 13 while IGT drops to 2. Does that sound that normal?

Another thing that seemed a bit wonky to me, is that my peak knock was 110 (This occurred somewhere in the lower rpm range, it appears while backing out of the garage). However, more concerning is the reading of 38~45 counts while in the few hundred RPM range of full throttle. I'm not sure what "normal" might be considering I have solid motor mounts and a pretty heavy ACT clutch.
I've also tried turning the boost down to 10 psi to see if it occurs at a lower boost level, and it still happens. I didn't get a chance to log my AFRs, but i did notice on my AEM gauge that as soon as the ignition break up occurs, it goes lean. I don't know if that is the cause, or an effect. The AFR jumps to about 16:1 pretty quick as the highest I've seen it. I immediately snap off the throttle as soon as I see it about 11.7:1

I have a host of parts to install, such as AEM water/meth, and an aermotive 340lph pump with the fuel pump wiring mod. As well as things like the AEM smart coil upgrade i'd like to do, but I need to figure this out first and I don't want to just throw a bunch of parts at it that might not fix it but render the car to be in a different state, or not running. Worst case scenario then, is that i find out i still have this problem while it's sitting on the dyno wasting a tuner's time who just drove 4 hours to tune my car.

Thanks in advance!