I have never seen/heard of it being done on a gas powered vehicle. I know that in a diesel vehicle that doesnt get driven often, sludge will build up in the bottom of the tank. Flushing it involves getting all of the sludge and old fuel out of the bottom of the tank, making you truck run better since the fuel pick up is submersed in that sludge at the bottom of the tank.
I would try replacing the fuel filter yourself, and running fuel system cleaner through it and see if it solves the problem. If it doesnt, have the flush done.