Hello, I'm new to this forum and could use some help. I have a '97 Ram 1500 5.9 w/134K miles. First problem was hesitation, truck would constantly hesitate on take off. Then second problem, on long trips (about 1hr drive) the Ram would start idling erratic and black smoke would pour from tailpipes. Friend had similiar problem with MAP sensor on Chevy. So I replace the MAP, problem seemed to be fixed.....wrong. Month later same trip, same exact symptoms, so I changed plugs(bosch plat.4) wires, cap, button(all mopar) and had upper intake flushed......no help at all(probably should have took it to dealer after this). Next I decided to try changing sensors out around throttle body. Changed TPS....didn't work. Changed IAC selenoid-valve.....helped shortly then back to the crazy idling again. Alright dealer time I suppose. Dealer said fuel pump was bad. $400.00 dished out for fuel pump module and hesitation problem seems to be fixed. But my idling problem is still happening, only now it's accompanied by the sound of air or vacuum of some sort. It's very loud sometimes when I first start the truck, and it seems as if it's gonna die(idle drops). Then I'll hear a click or snap of some sort that sounds like something has closed and the engine will idle up and run somewhat better and the air noise gets much more quiet. Upon raising the hood I can still hear the air but can't figure where from. I checked inside the intake through the throttle body to see if there was oil, indicating a plenum leak...but there's not any that I can see. If anyone can help I'd greatly appreciate it. I've done everything short of buying a new truck. I very seriously contemplating setting this thing on fire or running it off a cliff. Thanks in advance.