Well for struggling to say it in English I would say you do a really good job. In fact you do a lot better than some who speak it as their native language! Where are you from?

Does the engine die completely or does it just slow down like you were letting off the throttle?

The way these Powerstroke engines work the injection (fuel) is controlled entirely by the computer (PCM). There is no device that controls the flow of diesel. I am guessing that what was leaking on your truck is the Fuel Filter Switch. It would be on the side of the fuel bowl and just turns on the light that tells you (or is supposed to tell you) that the fuel filter is clogged and needs to be replaced. In any even, that shouldn't have anything to do with the issue you're having.

If the engine wants to die completely (like someone turned the key of) My guess is that you either have a clogged FPR Screen or a bad Camshaft Position Sensor (CPS).

The FPR screen can be cleaned by opening the fuel filter housing and removing the filter. On the passenger side you will see a hole about 1/2" in diameter a little way down from the top of the bowl. There is a screen in there that gets clogged and needs to be open for the fuel system to correctly separate any air in the system. You can cut the cotton off the end of a cotton swab and gently scrape that screen clean, or you can remove the whole assembly and clean it that way. Here is a picture:

Incidentally the round thing screwed into the side of the FPR is the Fuel filter switch I was referring to above.

The other thing that it could be (and actually this is a really good place to start) is that your CPS could be going bad. The CPS signal is required for the PCM to run the engine. If it loses that signal, it WILL NOT RUN. The CPS is located on the front of the engine above the main crank pulley at about the 11 o'clock position. Get one from Ford or International as the ones you get from any where else are complete JUNK and may or may not work at all. The part is about $30 here in the USofA. Here is a picture of that as well:

This one has the water pump off so you can see it really well but that should give you an idea where to look for it.

Good luck and be sure to report back and tell us what you found.