well, the odd thing is the *exactly* 30 mins issue. perhaps the car is having issues transferring short-term fuel trims to long-term fuel trims? can you log your trims and see what they are doing? the problem then shows up at 6000 rpm because the car will not go into open-loop?
or, the problem at 6000 rpm is a variocam issue - can you actuate your cams w durametric?
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