Pulsing sound at low idle

2013 tacoma access cab 4x4 v6 with 25,000 miles

So a few months ago while at stop lights with the car in drive and foot on the brake my truck will make a pulsing sound at low idle ( vreoooom, vreooom, vreoooom) like metal vibrating on metal but pulsing. It will only do it 2-4 pulses and then stop ( does not do every stop light just on some). I have tried extensively to re create the conditions but the darn sound happens so randomly i have been unsuccessful, plus its hard to pinpoint the sound inside the truck.

Ive crawled under the truck looking for loose heat shields skid plates ext but to luck, the sound drives me nuts and was hoping someone has some insight on what to do. I doubt the dealer will help because its hard to create the sound. If anyone has any ideas please help, thank you.

 

Check the heat shield mounted to the floor above the cats

 

Well since you're stopped, it has to be the moving parts unless it's a vibration of sort. Start in the engine compartment and check pulleys.

 

checked all heat shield and there tight

 

it sounds like a vibration but it pulses, how would i go about checking them?

 

Take off the belt and spin the pulleys by hand. Should be smooth to spin and no drag.

Also some things vibrate more when the transmission is on drive and not feel it on park at idle

 

Abs pump kicking on? Had that happen in a Camry before

 

My truck makes an extremely annoying sound too. It only seems to do it when my wife is riding with me. Suggestions?

 

Duct tape

 

There were many times where I wished I had duct tape but also plenty that I did and provided temporary fix.