Jeep MAKES AWHISTLING FROM UNDER HOOD

The problem you have is vaccuum releted. My guess is probally a cracked or loose line.A good way to locate the area to look is. Open hood with engine running and take a can of carb cleaner and use quick bursts of spray in different areas and listen for a change in the idle. The area that you hear the change in is the area you want to look for a disconnected or cracked line The vaccuum lines will be the small dia lines. The reason for the quick spray bursts is that you dont want to get it wet you want to create a fog to richen the air which in turn will be sucked in through the source of your leak. Im a bad typer. I hope it can help