Ford F-150 - 1997-2003 :: Running Loud And Heavy - P0171 - Vacuum Leak?

I've had this problem for a little while now, my 97' F150 V8 4.6L, has been running real loud and heavy. When it starts up it sounds like a race car. It finally shot me a code for P0171 - Bank 1 (passenger side) running too lean. From what I've read, this is most likely a vacuum leak but I don't know too much about it.

A couple of things I've noticed while driving it around:

1. If you are in the engine compartment while its running, you smell the excess gas on the passenger side of the truck.
2. The exhaust also smells really heavy
3. The loud and heavy running is mainly when accelerating, if I maintain a constant speed at for a little while it almost starts to run normal. Cruising down the highway its almost just as quiet as before the issue
4. Engine coolant heats up much more quickly, but doesn't get above operating temperature (read from tuner, never above 200 degrees)

In response to the problem I replaced both the O2 sensors closest to the engine and the PCV and elbow. No change. Have a fuel filter ready to install, but for some reason I don't think that is it either, as it would probably effect both bank 1 and 2.

Like I said I'm not too well versed in the vacuum system but if any of these symptoms stand out I'd love to hear your thoughts.