Picked up our new 07 Expedition and noticed it had very low power. Took it to the dealer and they agreed. They checked all the obvious and couldn't find anything. I finally couldn't take it anymore and traced the air intake back to point where it pulls air before the air filter, between the fender and firewall. A piece of rubber sound absorption material had come loose and made a perfect seal at the intake...totally blocking off the air flow. I pulled the piece out and no problems. I drove it 600 miles like this and hope it didn't do any damage.
After reading your post I went out and looked at my 07 and guess what? No the intake tube was not blocked, but the little black plastic push pin that holds the rubber sheet in place on the fender side was sticking out about 3/4 of the way and I just pulled the pin out by my fingers. I could see that if the pin came all the way out the rubber sheet could have just dropped down and worked its way in front of the intake tube inside the fender, leaving just those little holes that are for (what ever reason they are there for) the only way air could get to the engine. It is a wonder your Expedition ran at all. I pushed the pin back in and checked the inside of the intake tube. All clear to the fender. Every one should check theirs too. But you may want to put the rubber sheet back in as this adds to the ram air effect at higher speeds for more power.
Way to go Ford!