Hello, I just bought this Expedition and.

Hello, I just bought this Expedition and noticed has no power for passing at higher speeds, and also, when it downshifts, there is a rattling sound that seems to be coming from the transmission. Additionally, there is an intermitant buzzing sound, while going down the highway. Not loud, but loud enough to be annoying. When the car is in neutral, when revving the engine, it sounds good, no rattling, or buzzing, however, it seems like it doesn't rev properly. It doesn't rev up as quickly as what I've experienced with all my other cars over the years. It seems to have good low end power, but at higher revs, it just has no torque. These are two symptoms, but not sure whether or not they are related. I changed the tranny filter and oil, and also tried higher octane, and also Lucas fuel injector cleaner, but still the same. The magnet in tranny pan had the normal small bit of metal fine dust on it. I also changed the plugs in it as well, (nightmare)! When I have a chance, I will have a friend drive it, while I am in the back seat, with the door open and listening underneath to try to pinpoint the rattling underneath. Thanks so much for any help.
PS; I am glad to see that you have a reasonable donation requirement, at the bottom. I have no problem with that. Other sites that want to charge $25, $35 are way out of my league as I am a disabled vet. Thanks!