I have had a whistling sound since I bought my 99 Discovery II. Over the years I sometimes ignore it but recently...I have got to find it. All lines look good, but I am thinking of a cracked vacuum reservoir. Problem is...where is it? Another symptom is when I use the cruise control and it gets me to speed for about 2 minutes then it does it again and again, etc. which is clearly indicative of a vacuum leak. Any help? Thanks!!