I hope so. I'm thinking I'm going to pull the sway bar next and go for a drive. Part of me wonders if it's not something over tightened.

Pulled the sway bar, and that wasn't it. I made a pair of the det cans earlier this month, and started attaching them to different parts of the car. It is true, even at normal neighborhood no-boost speeds you will remelt the hot glue. I could hear the rattle on the exhaust, barely on the starter, and on the valve cover.I think I found one of the parts of the rattle, the radiator of all places. It was crystal clear through the det can. The radiator looked isolated all around the sides from hitting something. I hooked it directly to the radiator cap and the noise seemed to be a little stronger. It's an over the counter cap on a Koyo radiator. Going to try and find the Koyo cap tomorrow and see if that fixes the problem. Wouldn't this be the most trivial solution to an awfully serious sounding problem?

Unplug your rad fans and see if the noise goes away.

It could also be one of the pulleys from your timing belt starting to go.

Great diagnosis method!!! awesome!

Koyo cap did not solve the problem. I guess next weekend I'll pull the fans, drive around the neighborhood, and then if that doesn't work I'll pull the radiator. The radiator really looks pretty isolated from movement and rattles. I might pull the hood off and see if it's hitting the hood. There are no marks on the hood from it hitting it tho.

Just try jiggling the fan blades. I know one of mine squeak a bit when cold, and rattles a bit when warm. It's a 20 year old fan, so I can't blame it.

I did and it did make the sound in a very faint sort of way. I'm going to get the fans going tomorrow and go through the same set of instigation to see if still makes the noise. I think the fans have been off every time I've done this.