VE SV6 Stuttering Issue at Constant Speed - Post MODS

[kfcnaal]

Hi All,

I have recently installed some mods to my VE Auto 2010 SV6 LLT wagon. This has been an issue to say the least with the problems I have run into.
Need some input into some probable root cause to my current issue.
Firstly I had made the following Mods:
-2.5" Catback
-OTR Intake
-Tune
-Oil Pump (replaced)
Had some issue with constant CEL issues which have been resolved by replacing ECU.

Now since the new mods again, I am having issue which I am working with the workshop to resolve by trial and error.
New Mods:
-Extractors/Headers
-High Flow Cats
-210/210 Cams

The issue I am having is that, when travelling at a constant speed, I am experiencing Stuttering, firstly at 80km/h but can be seen at 80-100 randomly. It only last around 1 sec but occurs quite frequently (every 30 sec - 1min) when driving down a freeway.
Also has weird dips and ups of revs when accelerating (not major).
We have tried/ troubleshooted the following:
-New Timing Chain + Oil Change
-New Throttle Body
-New Spark Plugs and Coils
-New Custom O2 Sensors heat shielded
-New MAF
-New Alternator (which Failed)
-Multiple Remaps/ tunes of ECU

Still not fixed and running out of ideas, car has never overheated.
Please let me know if anyone has any idea of what I can try next to fix this issue.
Next try is replacing the fuel pump and carbon cleaning of ports.
I have always maintained proper service since I bought the car in 2019. Had a trans service at 150K currently at 180K. New Battery in 2020.

Cheers,
Kunaal

 

[MYVESSV8]

cam sensors, crank sensor and all connections for these,

 

[07GTS]

first thing id do is get a log of what its going so u can see the data, then u know if the dip/stutter is spark or airflow related or if the tune is doing something, then once u can see it doing it u can log more related to that area to try zone in on whats happening

 

[harrop.senator]

I don't know a lot about modern tuning but the fact it does it on maintained throttle and the rpm goes up and down without a speed change. I'd be looking at the torque converter lock up.