What I got:
'01 Cherokee Sport
2WD
4.0L

Ok. Best I can tell its coming from the driver side of the motor. Just finished replacing the valve cover gasket, water pump, and alternator. Noise does not seem to fluctuate. I can coast and the whistle goes away. Press on the gas whistle is back and it is steady. Prior to this symptom, I noticed a clickity sort of noise coming from around my gas pedal, under my food when I pressed it, but it seems to be gone. Oh, and my gas mileage seem to be going to ****. Literally, like 250 mp / Tank. Any ideas? Thanks, in advance.

 

Exhaust leak?

 

Could be a vaccuum line popped off or broke. Or somethin went bad in the air box. Like the filter getting a hole in it or somethin weird like that. Check some stuff around there, see if anything is out of place.

 

Yep... found it later last evening. Vacuum tube that connects to the manifold. The connecting boot was dry rotted and partially slid off. If you're on the side of the truck it was the far left one. The tube runs along the firewall to the far left corner. Can't seem to find what it actually connects the schematic diagrams. I see where it ends, but don't know what the part is. Maybe this will get my mpg back to normal. It has been slowly deteriorating the past year or so.

 

Can you post a picture? Someone might be able to tell you what it is. Im not sure if it's the same as my 89. I imagine they changed most of the old school vaccuum lines to electrical systems for a 2001. It should be an easy fix once you find the part name and number. Get it fixed as soon as you can.

 

Sometimes when i press on the gas i can hear my TB whistle.. Just a thought

 

Ok, now when I am sitting a idle it whistles. ?? I can't seem to find a vacuum diagram for 2001 Cherokee Sport 2WD, 4.0's? Now after finding that rotten boot, I wanna go through all of them.

 

 

Thats really different than my 89. Maybe someone can post a diagram on here to help you find all the lines better so they can be replaced.

 

I just learned that there is a little rubber elbow hiding under the map to connect vacuum. No idea if they leak but while you are listening for your whistle you might watch that as well.