I have a 97 Dodge Dakota with the 5.2, 5 Speed.. Recently i was on a long drive and all of a sudden i began hearing a hissing noise from what seemed like by the transmission and i also noticed a significant power loss as well. I did not get any check engine lights on and when i got to my destination and let my truck cool down and started it back up the noise was gone and power was back but farther into the trip the same thing began to happen again. I am thinking possible vaccum leak somewhere? I also noticed the PCV valve was hissing and when i pinched the line the hissing stopped. Any ideas?