2005 Dodge Ram Throttle Noise

I have a 2005 Dodge Ram Hemi 1500.

In the past two weeks, I have been hearing a loud noise whenever I give it throttle past 20mph, which becomes less audible as speed increases (e.g.: almost no sound at 70mph+).

At higher speeds/heavy throttle, it sounds like whistling (like a vacuum leak), but sounds like grinding/sputtering/misting at lower speeds/light throttle. This sputtering/misting sounds like when you put your thumb over an open garden hose, and let a little water out.

I first thought it might be the aftermarket intake, but that is cinched down tight with no leaks.

All the hoses are fine, no leaks in the exhaust, all fuel lines intact.

There are also no error codes popping up nor are any of the gauge out of their usual range.

I have not noticed any problems with acceleration, idling, or fuel consumption.

I have tried to recreate the sound with it in neutral, but again, the sound only starts when in drive.

I am starting to get gun-shy about driving my truck around because now there is a "turning down/off" sound when I slow down to a stop; it almost sounds like a Sawzall powering down, then nothing when I am stopped.

What I have done so far with no change to the sound.
- toggled between tow/haul mode and normal
- no change in the sound driving on surface streets or highways
- Seafoam (thought maybe buiding up near the throttle body or intake maniford). No dice.
- A/C on or off, fan on or off, but no difference.

I am wondering (not hoping) if it is the fuel pump?

Any suggestions? Thanks.