If anyone has a rattle around 2000 rpm that increases when you are under light acceleration byt disapears after 2200 rmp....and sounds like a buzz....heat shield rattle....it is, but not the top heat shield at maniforld but rather it is the lower one which can only be seen when you remove all skid plates from underneath.
This heat shield is welded to the elbow of the muffler just before it straightenes out to the cat.
I went crazy for 3 months to find it and finally removed the shield and rattle is gone.

Hope that helps.

 

sometime a metal piece that vibrates is fixed by bending it,hiting with a hammer,twisting with heavy pliers. removing may bring new trouble

 

YES!!! Mine just started rattling last week but is not doing it on the start ups I plan on jumping out and looking for the rattling. I had my wife start it while I looked over the weekend and could not see the manifold shield moving. It does sound like its coming from under the vehicle so I'll check that one out.

 

mine does it also at 1800rpm to about 2000rpm under light load lol!

 

Check the bolts that hold the underbody protection plates beneath the oil sump are not loose