I have a 1999 Mercury Mountaineer V8 5.0L. I have had to do a bunch of work (myself) to get the car running and get it where it would pass emissions. I've replaced the EGR valve, CAM sensor, plugs, wires, etc., etc. I got it running and the check engine light has gone out. The problem now is there is a high-pitched whine that a mechanic said was probably a vacuum leak, and.. the most embarrassing part... I have an extra tube that may/may not be related. I have literally removed everything I put in to see if I could spot where it goes to no avail. Does anyone recognize this tube and know where it might be located in my car?