I removed my throttle body to clean it the other day and now when i press the gas pedal at a certain spot it makes a high pitch whistling noise. I then changed out the throttle body gasket but it still hasnt made a difference and I am now confused so any help would be awesome!

 

Is the tb ported and polished? or stock?, my ported and polished whistled lightly for a long time and recently i noticed it doesn't do it anymore.

 

My dads 5.9 would do that. Me personally, I wouldnt worry about it but you can always lift the rear end and stabilize it and run through the gears carefully or try it in neutral also.

 

i got this same issue but its only when the truck is under load and at about 1/3 throttle. its been doing it for over a year and no issues have been detected from it.

 

I had a similar problem. It would whistle from start up until I turned it off. It was very annoying for a very long time. Anyways, the problem on mine was the Idle Air Control Valve. Once I changed it, it's only the sweet sound of a Dodge. If you take some throttle body cleaner and spray around the side (LIGHTLY) and the sound goes away, then I'm willing to bet that's the problem.