Yeah, if it's been a while or you don't know when the fuel filter hasn't been changed you should just go ahead a replace it. While the engine is running, pull the 30A maxi blade fuse for the fuel pump under the hood and let the truck die. That will relieve most of the fuel pressure. Just be careful when you pull the clips and fuel lines off of the filter because a little might come out on you (don't put you face right under it!). On mine, that resistor which I speak of is in a small yellow plastic rectangle with a wire going in on one end and other going out the other end. It was fairly close to the steering column and rapped up with electrical tape (from the factory it looks like) sticking out of the flex loom a little. It also said "resistor" right on it. To test it, I just took the leads on my multimeter which were fairly sharp and poked them into the wire on each side and was able to get a reading. Ford really should've had a better way to test it with connectors on each end or something on it. They should've at least mounted the damn thing. After you change your fuel filter you should look into your secondary fuel pump as being a source of your problems (I think that you have 2 pumps on your truck, one of which is located somewhere along the frame rail too). I guess you could unplug it and see what changes as a test. If you unplug it and it doesn't do anything, you know that it is dead. Someone with the duel fuel pump system can probably give you better pointers.