My 2002 tuarus sel idles rough when idling,whether its parked or in gear. I can hear a vacuum leak but cannot locate it

I leak that makes a squeal or a screech?
Have you recently had ignition problems or smoke from under the hood? We have seen this problem pop-up in about 10 different DOHC Taurii in the past two months. (60-80k mile region). I am not sure what the specific hose is but it is located below the throttle body and has a tee connector. On all of them but 2 it was the top hose.

There is no smoke or squeal at all,just the sound of sucking air when it is idle or in gear at a stop.It has a bit of a chug when sitting at a stop with the car in gear.

Hmmm?
Check the air intake for holes or lose hoses.

Have already checked that!! It seems to be somewhere at the back end of the engine.

Be sure to check the hoses on the PCV system, they're always bad about rotting through.

Check the air intake hoses below the throttle body....the ones that look like they would going toward the tranny or the actual engine block.