Wierd noise help

[firmbiz94]

I have an 05 v6 lincoln with 60 k..lately when i have my car in drive and step on the gas im hearing a wierd noise..kinda of like a rattle..its hard to describe..when im in neutral it wont do it but with the throttle by wire i cant really rev it up so i dunno.. it will do it at any speed when i step on it a little bit. Any idea what it is? Hoping it isnt the tranny

 

[firmbiz94]

no one?? tranny shifts find but only does it when im accelerating like i said..can it be my cat?

 

[tireman]

Could be?

Could it be your heat shield on the cat or muffler is loose?