I agree with most of the people about the valve adjustment and especially V-Tech engagement, but also on a sidenote, make sure the engine is warmed up properly before you drive...and does your fan turn on after a long drive??? Mine didn't and i heard that it does after pass a certain mileage. I think it's 60k not too sure though. If not try wiring a switch to it so you can cool it out manually. I did it because I wanted to cool off the engine after racing on the drag strip. Just a suggestion...not really a solution!