I just bought a 1997 Taurus 3.0 daily driver. It is really nice and the price was especially nice at 1500. I noticed when I start it up in the morning it has a small tic and then after it warms up its virtually gone. It doesn't get louder when you drive at high speeds but, when you drive in a garage or close to a wall you can hear it. What could this be? Is it a rocker or rod or what? Can I fix this without rebuilding the motor?