Ok, so now everytime i start my car, for the first few minutes, there is a rattle coming from somewhere underneath the car. It happens only when cold, which is the key part leading me to think it's emissions, as whatever it is may turn off as the motor rises to operating temp? The car is an 83', all stock, with absolutely no modifications. So if anything knows an emissions part to check up, or where to look in the exhaust, please let me know. Thanks!

 

Check fo loose heat shielding.

 

I had the air pipe going to the cat touching the frame. Easy fix, just reached under the car and moved it a little...