The servo motor for the cruise control might be bad. It is mounted on the firewall just behind the drivers' side strut tower.
The original servo went bad on my car and I replaced it with a used one from a '95 Contour... about a year later it went bad too.
I got a complete cruise control kit brand new from someone on ebay for just $30. I swapped the used servo for the new one and it has worked perfectly since.
I'll look to see if they still advertise it.
Here's a new kit for $50... it will probably solve your problem and is worth the price:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33595&item=7963065701&rd=1&ssPageName=WDVW Then you'll have a bunch of new extra parts to either sell or use to decorate your next Christmas tree.
Word of advice... my cruise kit came with 2 cables... one for the 2.0L and one for the 2.5L. Neither fit my car properly. One was way too long, the other about a 1/2 inch too short and held the throttle body open all the time. I had to use the original cable which came with the car.
