and a buddy of mine owns a shop and the 6.0's pretty much could keep him in business pretty easily, and a customer of his had this happen to him right after he installed an egr delete and the basics,
IPR said it was functioning properly, still no start, then he kept trying it, and it would never go, so he just replaced the
IPR and sure enough it fired right up, I'm not saying it's your problem, but he now replaces the
IPR every time and EGR delete is performed