I have an 03tl S. I get a little vibration on the highway at 60-70 mph, but I cant figure out if its from the engine, suspension or wheel/tires. Its worse in 5th gear and diminishes when I shift to 4th. It almost feels like the engine is lugging. Just to make sure I had all tires balanced, etc. O2 sensor is a though, too. Anybody with some ideas?