That sounds very similar to my 2004 V8 when the bearing on tensioner pulley for the serpentine went bad and I had to replace it...but it could be the idler pulley bearing as well, or both, remove your serpentine belt and spin both of the pulleys and see which one or both is noisy and or hard to spin freely.

Also just an FYI if it's the tensioner bearing, they comes with a new pulley on it, just remove the bolt and install the new one...but there are 2 sizes when I went and got mine, the earlier 2003 and 2004 V8s have a larger pulley then later V8s so roughly measure your's before buying the new one, they're measured in MM and I can't remember the exact size in mm but mine was right at 4" (I think this was 100mm or 101mm) and the newer ones are around 3 1/2" (I think this was 90mm), this also makes the serpentine belts a different size as well, I didn't have to replace my idler but I think it's the same size for all the V8s but I'm not certain on that, and they also come with a new pulley on the bearing.