Here's a link to the sound I'm having:

http://www.youtube.com/watch?v=_smh4...ature=youtu.be

This only happens when the car is warmed up. I've read here that it could be the SSV, but to be honest I don't even know what that is or what it looks like. Also, when I started it up last night it was running REALLY rough and the CEL was blinking. I restarted it and it went away, and I've driven it around today and it drives just fine.

It might be worth it to note that it does make another weird whistling sound at startup. I've already checked the spark plugs for the chattering sound and it seems like they're on just fine.

Does anybody have any ideas?

 

Also it's been doing this for months. No idea if it's bad for the car or what. It's only ever started up rough once, and that was last night. Not really sure what to make of it besides maybe old age? She does have 139k miles.

 

whistling could be the air pump, it will shut off after a bit.

See if the noise is coming from the valve in front of the air pump. It is the round thing in your video in front of the air pump. That exhaust pulses could be knocking the inside of the valve around. That is the best guess I have.

 

And if it is that?

 

Take it off and put on a block off plate on the manifold

 

I wouldn't even know where to begin. I'll check in the morning if it's this valve, but I'm not sure it's even bad for the car for it to be making this noise. It's really not as loud as it is in the video, especially with the engine cover on and hood closed.