I’m have the same problem and I’m pretty sure it’s a vacuum leak. After a few minutes of riding the noise starts. You can hear it when u come to a stop are if you take your foot off the gas. When I check under the hood I notice if I take the dip stick out the noise goes away but as soon as I put it bk on the noise comes right bk.I have a 2008 land rover lr2. It just started making an incredibly loud whistling
noise yesterday. I removed the engine cover to observe the intake system or perhaps the alternator belt as well as the power steering. the noise is not coming from either alt. or ps belts. It sounds like a loud vacuum leak. The check engine light has come on listing codes p0171 and p0174. Has anybody had this issues that could offer any tips or advice?