Changed the oil and filter and got new plugs. It's been 50K miles since they were changed anyways (the plugs that is...). The engine was in good shape to start so I don't know that I'll notice a huge difference, but valve noise has been significantly reduced. I'll definitely be sold if mpg's are affected. We'll see. How about the O2 sensor? Is it "cleanable"? Is it worth removing and cleaning it or should I just leave it alone? The plugs didn't have any noticeable buildup so I'm not sure the sensor will be much different.