This will be a good start to finding your issue. The 4.7 motor is packed in there as is the Hemi. Take your time and check all visible rubber hoses.
Be very careful though when doing this with the engine running. You dont' want to lose an arm or finger!!!!!
It is possible you could be dealing with an exhaust manifold leak as the 4.7 motor is famous for loose/broken manifold bolts.
2004 Durango SLT AWD 5.7 Hemi Flame Red with 3.55's (Mine)
05 Dodge Grand Caravan SXT 3.8L Linen Gold Pearl (Hers)