04 4.6 has no codes just idles rough. And really bogs way down in gear has no power. I pulled the module off found a crack in the back of it. I know this needs to be fixed asap. But could this cause the above issues. I' not getting the code from the module that I have read about. No misfire codes either. I can' find a test for it or if unplugging it will help to test it.

 

No you can't test it .No your symptoms are not caused by this . usually fpdm failure cuts fuel off and she won't start or run/shuts down intermittently . .
You may have misfires that have not reached the threshold of setting codes . There could be other things but you need to have plug circuit in good shape first . How long has plugs been in there .

 

I' say a good long while I have had the truck about a year. I've got some plugs on the way for it. Was going to start there also read about the throttle body so cleaned it. One thing I notice is raw fuel smell which makes me think plugs are bad.

 

I know we torque the 5.4 down 25 to 28 foot pounds . Loose plugs have accelerated failure . It kind of like holding a cutting torch to the plug, burns them up with the blowby . Some plugs will launch ,take cop with them and the threads too.

 

A misfire count can be found on some code readers like torque pro under mode 6 . Check that out after plug change if shes still acting up .