2005 Chrysler Pacifica (Front End Hum)
 

The noise sounds like the engine is racing (it kicks in pretty loud at 40mph and continues up to 60-70mph, and then stays all the way down to a stop). SO it doesn't feel cyclical.

It's as though something has suddenly gone out of balance.

The trans shift pattern is fine. RPM's don't go past 2300. It operates very well.

It sounds a bit like loud tire/road noise, but the tires a fine (and I rotated in case I couldn't see a belt issue).

It comes with a vibration that can be felt in the steering wheel and both pedals AND the cooling fans get really loud when sitting at idle (I can't tell if that's related at higher speeds).

It's a front wheel drive, too.

Any ideas?

Sounds to me like a front wheel bearing hub assembly needs to be replaced. The best way to find out which one it is would be to while traveling straight line slightly turn the steering wheel to each side and see if it gets louder. Kinda like they do in Nascar when they are warming up their tires just don't do it so violently. Only need to turn a hair to each side while going about 55+ to hear the difference. Usually that is how I can tell one needs replacing. I recently replaced the drivers side one on my 06 Pacifica. ;)