My "m-chan68 crystal ball" is calling either a bad cylinder head #3 (be it valve(s) sticking in the guide(s), bad folower(s) or cam lobe(s), etc.) or bottom end issue with cylinders #6 and #8. A very easy way to rule out valve timing, would be the answer to the question "does it set a HARD P0340 fault?" If the answer is NO, then valve timing is NOT the issue. Another way to rule it out, is to see if you can view the power balance graph. If I'm not mistaken, a pop-up screen will appear, indicating CMP and CKP are out of SYNC if valve timing is out. In a nutshell, my vote is on a base engine concern.