Can also cause "detonation" which sounds like what you might have there... could be leaky valve guides. (could also be cam timing) check the condition of your plugs in this way...
Get the motor hot and be somewhere that you can pull off the road into a lot or safe shoulder or your driveway.... then while running, shut down your motor using the key, and immediately pull over. This way you can better see if there's unburned
oil in there... at least this is the theory I was taught. Check each cylinder before taking off. Just a long shot, and I would think there have to be other contributing factors .
__________________
James Madison, father of the Constitution, said, "If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy." He also said, "No nation could preserve its freedom in the midst of continual warfare..."
~~~~~~~~~~~~~~~~~~~~~~~~
http://www.standdown.net/index.htm