I give up....

My truck started idling a little rough about 2 months ago. Now it idles a little rougher, especially if it's cold outside(or it's raining?!?!) . This rough idle shook something loose under the hood. When I'm slowing down or whenever the truck is at about 800RPMs something rattles. So I'm taking it to the dealership(still under warranty). Time to undo some Mods...

 

I would guess it to be a malfunctioning oxygen sensor....But with the characteristics of it being cold and rainy, that also doesn't sound right...Besides, i don't know too much about that (yet)....Let us know what they diagnosed it....

 

It's nothing major. I took a technician for a ride and he said the rattle definitely sounds like a heat shield and since I only happens when I'm slowing down, it's not an engine problem. He said to correct the rough idle they're gonna replace the motor mounts and possibly raise the idle RPMs to correct the rough idle.....I hope that fixes it.