I have a 96 ram 1500, 5.2, 318. I've had this problem for a bit and it's just been getting worse. I start the vehicle and it runs fine for a minute then it starts idling really rough like its sputtering. And as that happens this loud hissing noise from the throttle body starts. I tracked it down to the butterfly valves on the throttle body that's making the hissing like too much pressure or incomplete seal but I'm not sure if it could be a sensor or mechanical. Then it'll catch up go away and do it again. When I hit the throttle a bit it runs like it should but when i let off it starts again. Any ideas what this could be?

 

Disconnect the front O2 sensor, and see if the problem goes away.

 

X2 when I had that problem it was the front O2 sensor. Throttle body is probably due for a cleaning too.