You are correct. Camshaft deviation is what I meant. After a 1/2hr drive I plugged in the durametric and got 1.0 degrees. So in spec.

But still got that stumbling. No codes or CEL. While rolling, I shut off the ignition and restart and it seems to go away. Very strange.

Interesting that you get 1.0 degrees of deviation on it with the mileage you have.
I wonder if the electrical gremlins your having with the CLU are also manifesting in other areas? Such as the stumbling.

Yep. Possibly.
I have an invoice from PO that shows an engine replacement 100k kms ago. So while I have 176k kms on the dial, my motor may be younger.

Well I pulled the insurance off today. So won't really get much testing done.

~500 kms since the O2 sensor swap. And have not had a CEL yet. So I think it's safe to say that there has been a positive benefit to making the swap.

There is better performance overall I think.

There remains a stumbling at higher revs occasionally still. But i'll chase that down next "driving season".

Over the winter I'll look into the SAI, get the CLU fixed and if I feel ambitious, maybe venture into the variocam actuator world.

Thanks again blue62 for following along and making suggestions.

Hope I was of some help;)