raddle noise driving me CRAZY

I have this raddle that is driving me crazy. It sounds like one of the heat shields, but I've checked and they are tight. It started after I changed my plugs and did an LOF. I made sure that everything I took off is tight.
I did a search, but found nothing. Any idea's?..Thanks

 

You gotta say under what conditions you hear it, and where it sounds like it's coming from, as well as how loud.

 

Not Saying this is it, but my last GMC did that really only at an idle or low rpms. I traced it to the Cat - loose baffle plate. IF it is it should be covered by powertrain/emission warranty... Hope it's not that.

Did you move any sheet metal used for heat shielding on the engine ??