Anyone have any ideas at all? Around 2000 rpm cruising i get an annoying ratling sound like a dustshield but all my shields are tight and dont really move, i had one idea that a cat might be coming apart on the inside but im not popping up any codes for a bat cat...

 

its a 2002 with the stock 4.2 with around 160k miles and all thats done to it is a flowmaster dual cat back

 

The heatshields may be tight but they could be contacting something, I had that issue and had to loosen the bolts and shift them a bit. To check for a cat coming apart, get under with a rubber mallet and start hitting them, you will hear it.

 

Also check your engine hoist brackets.

 

Thanks, ill see what i can figure out