the motor on my 07' 2.5i 5M starts to buzz around 4K rpms and the power drops of a lot. Only paid attention in 1st gear, since it is more noticeable there, and more of a problem. Sounds like the valves might be floating. Is this normal for the motor ? I was thinking of trying a cold air intake, to try to nudge the power up a bit higher, but not sure that would help now.
VF