My wife's 2003 Focus SE 130,000 miles, has recently started having a rough idle when the engine is first started in the morning. Once the engine warms up it seems to smooth out and run better. This has happened for about 2 weeks now. Just before this problem started I had just replaced the air filter. I do not know if this is related but I get no check engine light. I thought that perhaps the spark plugs and wires were the problem but I changed them and still have the problem. Has anyone else had this problem?