2007 Tacoma "muffled" sound under hood

My 2007 Tacoma (TRD Off Road 4x4 double cab) has started making a "muffled" noise from the front passenger side under the hood. The check engine light is not on and it makes the noise AFTER the engine has warmed and is idling or at very very low RPM. it is a low pitch muffled sound like something is going on with the exhaust, everything is stock (K&N air filter) on the truck and it has been well taken care of. I have searched all over the net and have found no information on this. Any help would be greatly appreciated.

 

Posting a video capturing the sound would help alot.

 

I had a weird vibration come from that side, about 1 month it took to me to figure out it was the plastic heap of the intake. The rubber bushings will not allow it to sit tight to anything it is mounted to. Same for me, only at low rpm's have someone apply pressure to random pieces of it or hold on to it and see if it stops.