I had the exact problem with my car. The problem with my focus was the valve cover gasket. The old one was letting the smallest bit of oil out and cooking on the exhaust header. The old gasket was brittle and stiff. I did this change around 150,000 miles on my focus. I hope this helps you guys.
The repair is so so so easy for the DIY. A gasket can be purchased for around $40 at an autoparts dealer.
Wednesday, April 2nd, 2008 AT 4:23 PM