Hello and thanks for using Just Answer.I will try my best to help you with your question.
The best thing to do is have the ECU(engine computer) scanned for codes. Any auto parts store will do this for you for free. The codes will pin point what is causing your problem. Throwing parts at the truck only cost more money and grief. Get the codes and post them on this page.
Sorry should have put this on the first message. Have had the truck on 3 different computers. The only code was low voltage on the throttle position or assembly and that is why I replaced it. Is there a computer that would read additional codes that the other ones that I put it on would not? 2 of the computers were from a mechanic from where I work and they work on fire trucks, all diesel and he was a ford mechanic before that. The other one was from a friend of mine who has a friend that owns a garage and put it on his and no code. Even after the check engine light came on??
A newer Snap-on scanner will work with the IDM. Either a Modis or the Solus. These 2 I know of .
The IDM does not control the fuel pump on the frame rail. The ECU controls that. The IDM controls the fuel injectors.