that would be my car that Jack is refering to, and I agree with the sludge theory. I spent the first 2k miles changing oil every 500. I also started with Marvel mystery oil as recomended on this board.
P.s. this reply is not to boost my car, but to offer my opinion.
I was told by CCR,inc. in colorado that the auto has the highest hp to make up for the drivetrain losses associated with automatic transmissions, and accoring to one of my manuals it also has the strongest valve return springs to help it rev higher without valve float.
This is my fourth (not on this car) EA81 that I have had the pleasure of driving, and it has definitely proven to be more powerful in the high end with only a mild loss in torque. Also I have never been able to run 87 octane fuel at 10 deg until this motor. Definitely a different cam profile as suggested.
Also I bought it from a company that guaranteed it for a year because they do a leakdown and compression test, as well as a rotating assembly test, at least that's what they said.:-)