Sounds like you & JMD are on the right track, normally you'll find its one of the idler pulleys (one above the crank damper, one upper left of the engine)
TBH tho unless you know if one or the other has been changed previously i would go for replacing both as they both do the same amount of work and get the same amount of wear.
With wanting to scare you tooooo
much its better to do them as soon as possible as if the sieze up,the belt burns through and then you're left with no cooling,power steering of electric charging,normally at the most inconvienent moments (Yep it happened to me [
On the bright side i reckon the 2.3 was the best engine they did [
It's not a job,it's an adventure !!