my engine light came on... Power loss... What does this mean?
Check your vacuum lines, a hissing that loud should be easy to spot, but will cause both. To be sure go to parts store and have your code read, sometimes a sensor will break inside and cause the noise.
my 99 just did that, and it turned out to be the water T that screws into my manifold. the nipple on it was cracked and it finally broke. I replaced it and my engine light went off and the car runs a lot better.
Search Ford Expedition Questions
Ford Expedition Experts