Sputtering/fluttering sound around 2500 rpm

[vertebrate]

Today my 2000 GTP started making a sort of sputtering/fluttering sound starting right around 2500 rpm. It's maybe a vaguely metallic sound, but not overly so. 2500 is right about the same time the boost is kicking in on the SC, so I'm thinking that might be where the problem is. It also only happens when in drive, not in park.

I'm not at home right now, but when I do I'm going to try popping off the SC belt and seeing if it goes away. If it does go away, any idea what I am looking at/for being wrong with it? What next steps should I take?

Thanks,
Steve

[vertebrate]

I took the SC belt off this morning, and am still getting the same problem. It didn't change where it becomes audible. You can barely hear it starting around 2000rpm, and around 2500 it's very obvious. I'm fearing bad things here. Any ideas?

[FordMan77]

Can you narrow down where this noise is coming from? Could be any one of the pullies, a rattling converter, cracked flexplate, etc.. Maybe remove the drive belt for just a short drive (like less than a few minutes) just to see if it's one of the accessories causing it. Could be the A/C compressor.

BTW, with no belt you have NOTHING. No coolant moving, etc.. so keep it very short.