Apparent engine noise and loss of power @ 3,000 rpm

[Brainfor]

I have a 2006 e450 u-haul truck with a 6.8L v10.
It loses power as my rpms increase, and if I put my foot in it to try to accelerate, once I reach about 3,000 rpms it sounds like there is smoke knock as if the timing was off. When I power brake it, it won't break the tires loose, but the smoke knock sound isn't there either. (Sorry, I didn't notice the rpms while doing this)
It is not throwing any codes.
The spark plugs are new, as well as the fuel filter. The OBDLinkMX+ code reader was used to check engine performance, including looking at the non adjustable engine timing and everything looks good.
I did fight a little overheating on some long grades, that turning the heater on took care of. Finally, while accelerating I lose my AC. I know that this is a result of a lack of vacuum, but don't know if it is normal for this rig or not.
Does anyone a have any ideas of what my problem may be?

 

[rusty ol ranger]

Code reader can tell if the timing chain is bad?

The 3V 5.4's are known for timing chain issues...i cant aee why the 3v V10 would be different

 

[19Walt93]

We had an E450 ambulance with similar symptoms. the substrate in the cat had broken up and pieces rattling around made the noise. The melted substrate killed power.
I don't remember any 5.4 timing chain issues, a bunch of the 3v engine had cam phaser noises.

 

[Curious Hound]

The loss of A/C is probably due to the WOT relay cutting it off while you have the throttle wide open. It’s supposed to do that so the A/C isn’t robbing power when you need it.

 

[Uncle Gump]

Plugged exhaust...

 

[Brainfor]

Code reader can tell if the timing chain is bad?

The 3V 5.4's are known for timing chain issues...i cant aee why the 3v V10 would be different

The friend that had the code reader and was helping me out wondered about the timing chain, but whatever he was deciphering from the reader made him feel that the chain and or guides wasn't it. I could ask him the details of how he came to that decision.
Thank you.

 

[Brainfor]

We had an E450 ambulance with similar symptoms. the substrate in the cat had broken up and pieces rattling around made the noise. The melted substrate killed power.
I don't remember any 5.4 timing chain issues, a bunch of the 3v engine had cam phaser noises.

The cat is something that we haven't entirely ruled out. I believe that when we checked the vacuum under load everything acted like it should, but it was suggested that I try to find a back pressure gauge and double check that the back pressure is within specs. The only thing with that is that I would think that the 'engine' noise would have shown up when we power braked it... maybe not enough exhaust flow?
The rpms need to be above 3,000 in order to get the 'engine' noise, but I suppose that the higher rpms would give me more exhaust flow that just being under a load...
Thank you, I'm going to pursue this angle further.