The TPS is really easy to change, but unfortunately its one of those readily changed parts that the dealer is well aware of how often it goes bad -that means it could be costly (considering you'll have to get it from the dealer).
My power issues turned out to be a misplaced vacuum hose not reconnected by the garage. Took three weeks to find, due to its location. If there is a junk yard nearby, consider getting one off a wrecked vehicle. The removal of it from a wreck will give you an idea of just how easy it is to replace.