A sticking throttle is a common sign of a dirty throttle body. Try cleaning it before doing anything else. You will be surprised at the difference it makes in performance, especially light throttle acceleration. In my opinion, this should be a maintenance operation that should be done at least every 30,000 miles (along with cleaning the injectors). I do mine every 10,000 to 15,000 miles. The last time I did it the difference in performance was HUGE.
According to the factory, the throttle body bore is coated with teflon and therefore never needs cleaning. Clean it anyway, just be careful of the teflon. The teflon makes it easier to clean and seems to cut down on the sludge that forms. Since they started using teflon, dirty throttle bodies are not as big of a problem as they once were.
Once Ford started using the teflon coating on throttle bodies, they said they would no longer pay warranty claims for cleaning. That left the shop with the option of replacing a perfectly good one (and getting told that they were getting high on warranty) or cleaning it and risking not getting paid. There is absolutely no advantage in replacing a dirty but otherwise perfectly good throttle body.
Rarely, there is more wrong with a sticking throttle body. If it still sticks after cleaning, it may need to be replaced. If it is out of warranty, it is worthwhile to try adjusting the hard stop idle very slightly. If done too much, it will throw off the throttle position sensor setting as well as perhaps cause problems with too high of an idle.
For information on cleaning the throttle body, try a search. This has been explained several times in the past by myself and others.
