2000 f150 5.4l
Truck has been rought idle and shutting off and also have hard time starting. New plugs, coils, fuel filter have been done. So I changed the IAC valve with a aftermarket one from rockauto. Truck would start then immediately shut off new code is iac circuit which confused me also threw more codes such as gem module, Vehicle speed sensor and other accessories codes. Noticed a vacuum line from the throttle body to the purge valve is bad so will be changing that next. Any help with this cause I'm getting stumped

 

May as well throw an EGR valve at thing while you're at it. It will surely kill it after firing if it sticks open.

 

Did get the code for that but went away but it's getting changed also. Grabbed a 2nd iac valve to test it and got new pcv valve and vacuum line that goes to the iac to the evap. Just replacing stuff that I see while it's not running since I got someone checking the gem module.

 

Fix the OBVIOUS problem ("bad" hose) then re-evaluate before doing anything else.

A severe vacuum leak will cause your stated symptoms.

 

Every issue i have noticed has been changed but after scanning with code reader (snap on) it showed issues with gem module. Had mechanic look at it and the fuse box and gem are both shot.

 

The PDB gets that way in the engine compartment as well. Hard to tell unless you lip it over....could be a sea of green. Hopefully all it needs is cleaned.