Check your idler pulley. I've seen a couple cases of this in Saleens (mine as well) and it seems to be this one quite often. Mine had the exact same symptoms and it made a pretty annoying buzzsaw noise. Check it out, it could be either loose or off center and sometimes requires replacement. It'll fix the problem right up.
And yeah, I've had my fair share of people taking my car out. Drove right past them driving my car, and driving it HARD. I followed them right back to the dealership and raised hell, and they were "making sure it was working absolutely correctly". I think someone got fired over it. Now, I always check my odometer before and after. Nothing like finding out the second time I went to the same dealership that they had driven it 75 miles (!). And yeah, someone DID get fired over that!
By the way, am I the only one not going by number?

01-216!