Hello everyone. Sometime ago I got a new noise on my 03 Ram 1500 5.7. I hear a whistling sound around the passenger floorboard/firewall area (really hard to pinpoint the location), but this noise only happens under a light acceleration when at speed around 45+ mph basically in overdrive at low rpms, if I press the gas pedal down further it goes away entirely. Makes no sound whatsoever when not moving, no matter if in park or neutral/drive, and revving in park doesn't make the noise either. It's loud enough that people driving next to me on my passenger side can hear it, my friends have told me. No check engine lights, no loss of power, decent mpg. I've recently cleaned the throttle body, changed the idler pulleys and belts, other pulleys are fine. I thought it might be a vacuum leak but wouldn't that also whisle when at idle? It's definitely towards the passenger side. Any ideas how I should further look into this? Many thanks.