97 9000 Turbo: Ticking in Engine Compartment

I've read a few posts and answers about this, but am still not sure what it is. Symptoms: Ticking that I can hear in the cabin, coming from the engine compartment, and from outside with hood closed. Can't always hear it so well when I pop the hood because of the engine noise. Can't really hear it at speed, probably also because of other noise. Can hear it best when idling or going slow. Ticks about 3 or 4 ticks per second. When I gently press accelerator ticking stops for about 1 to 2 seconds then resumes.Ticking doesn't speed up as I continue depressing accelerator. Taking advice from previous posts about this I looked for where it was coming from with a stethoscope; maybe coming from fuel injectors but I really cant tell with other sounds. Sounds like it might be coming from area around rear pulley of surpentine belt, but can't tell about that for sure either. Definitely coming from passenger side though. If I put my ear to the passenger side fender it's loud. If I try that on the driver side: nothing. Also... comes and goes - doesn't do it all the time. It may be ticking when idling after driving, I stop for a couple of minutes and it doesn't tick at first when I start it up. I originally heard this about six weeks ago and it came and went since then as well. Seems like I had the same symptoms once on a previous 9000. Any thoughts after this overly detailed description of symptoms, aside from psychological analysis of neurosis?