Having had a another think about this.

Rexy, try disconnecting both left and right AVCS solenoid electrical plugs and then going for a drive to see if your problem still appears. The AVCS Solenoids are to the front left and right on top of the heads (in front of intake manifold), same type of plugs as the AVCS cam sensors from memory.

Your AVCS system is likely to throw up a CEL (Check Engine Light) but don't worry as the Cams will just default to running on their grinds. There should be a loss of mid range torque though which will be noticable when driving.

Go for a test drive and see if the jerkiness during WOT disappears.
If it does then you have an AVCS solenoid - Oil pressure issue.
I would then reconnect the plugs and do an oil change to Mobill S 10w-40 Semi Syn and see what occurs.

However if the jerkiness is still there during Wide Open Throttle with the car loaded up in 4/5th gears you have a different problem. It will be dyno time with Engine logging to really see whats going on.

J

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