04 F150 engine noise under load any speed
 

I cannot find the exact issue so here is my problem 2004 f150 5.4 and under a load at any speed even the slightest incline Im getting a rattle somewhere under the hood cant tell if its left side or right? If I let off the gas it stops, and if i give it more gas and get it to downshift it stops! It has been doing it more and more not sure if its cause I have had the A/C on or what! Its not a rattling heat shield, sounds like air, OR???????
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FYI last fill up I put 89 octane in and the rattle has gone away so far!!