That was silly to replace the vp, almost just throwing parts at a problem. You should verify 5v at apps, possibly ground ecm and pcm externally. I may even consider regrounding the apps circuit. You need some actual data before replacing parts.

 

Your right on that statment, Its unfortunate that this happens, sadly it happens alot, Hopefully he takes some of the comments and can find the problem,
R---

 

Forums : misinforming vehicle owners since the beginning!

If you have to ask what is wrong with questions on a forum then chances are you don't poses the knowledge or correct tools to properly diagnose your vehicle. You.may be able to repair it but diagnoses is a technicians job. Anyone can swap parts.
Tuning and what if scenarios I understand , but we can NOT properly diagnose your truck from a computer screen.