When the engine is cold there is no noise. At operating temperature after pressing the accelerator, a loud shrieking noise comes from the engine. It sounds like a fan belt slipping.
On closer look, the noise is coming from the air breather. When I put downward pressure on the air breather the pitch changes and it returns to the original pitch when I let go.
I've read about others who have had noises with throttle body spacers. I don't believe mine has one.
I've removed the breather, used a cleaner to get rid of the minimal amount of residue/carbon that I could see on the throttle body. Didn't work. Then I replaced the gasket under directly under the throttle body, unfortunately that didn't work either. I'm wondering if there is a part inside the throttle body that might have come loose or if air is getting in from somewhere else that is creating that whistle-type noise. I even tried calling the dealer about purchasing a new throttle body but they aren't available.
Any other suggestions would be appreciated.
I'm new to the Jeep world and this forum, so my apologies if something is out of place.
1997, Wrangler with 2.5 L.