one problem to looks for is your CPS (cam position sensor) going out. it tells the computer what position the engine is in. if it goes out, the engine won't start/studdering/sudden shut downs.
another one to look for, there are four sets of electrical harness under the valve covers that control all 8 injectors (1 for every 2 injecters). the one that controls cylinders 6 and 8 has a design defect (driver side rear two cylinders). Ford fix the problem. don't know when they fixed it, you may have the bad one, it'll go out at random times. mine went out back in January of 2006. smoke was coming out from under the valve cover.
any other problems as far as i can tell are just the user abusing/not taking care of things.