Awesome job by the OP xjcamaro89. That post saved me a ton of headache and money. My 08 5.4 started making (what I thought was) the noise yesterday. After reading this thread the first thing I did was unplug the IWE solenoid electrically. This made the noise stop.

The next thing I did was test the check valve closest to the solenoid and sure enough, it was bad. I'll be picking one up from the dealership tomorrow.

Andy