Mine had a weird rattle that i couldnt figure out, and after driving, listening , different rpms, etc, finally put it on a rack and found a branch stuck up above the drive shaft. No idea how it got there.

 

If you have an old garden hose you can chop it into a 4ft lenght and use it to isolate the source of the noise. Let us know what you find.

 

If you have a DP is it a 3incher??? Have you placed spacers on the brace bar underneath??? If so double check to see if the bolts are good n' tight. This was my case, the car woould make a loud noise almost comparable to a heat shield coming loose. The bolts were stripped and not holding the brace as good.

 

The only accessory the timing belt runs is the oil pump.

 

I had a mysterious rattle as well. Found it to be coming from the A/C Compressor. Few weeks later the A/C compressor completely broke, leaving the pulley able to move side to side.