97' Mercury Mystic

The car idles rough, like a vibration. It has 79,500 miles. What could be the problem please. I would like to fix the problem myself if I could.

She needs a fresh set of spark plugs, an air filter, and a fuel filter (if accessable).

In addition to hellokit’s suggestions I would add cleaning the Idle Air Control valve.

Thanx to both of you. I will try those ideas.