2001 Ford Expedition • 160,000 miles

Since, my SUV had both heads changed, it is burning oil at a rate of 2 quarts almost a week. I had it checked for oil leaks, it is not leaking any oil, what is happening? I did not have this problem before, at that time I had all the coil packs and spark plugs changed; this was around March of this year. Now, when driving, it stalls in the middle of the road at random and it takes for you to continue mashing the gas to the floor, then eventually it starts to go, but i've noticed a noise under the hood, like something is falling a part, but when checked nothing seems to be wrong. What can I do to solve some of these problem, I am at a loss, literally.
November 15, 2012.

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