If it's only at idle, it could be your Idle Air Control module/motor ("IAC"). Common problem, easy fix(es).

I love my Contour to death, but my 'vette is still my #1 baby.
There's money to be made in racing. I should know. I put a lot of it there.
You can make a small fortune in racing. Start with a large one.
How fast do you want to go...how much money do you have?
You can fix a lot of things, but you can't fix stupid!