Mine's been doing the same thing. Started about 2-3 mos. ago. So I figured it'd been a while since I've changed my fuel filter, so I did that & it seemed to clear up for a week or two. Then it wasn't every morning, it was sporadic. Just recently, in the last couple weeks, it's doing it again. But mine sounds like it's got a wicked cam or sometimes, shitty gas. Yesterday, I go to clear my DTCs since the lights on & instead of the usual po420, po430 it also had po170 & po174, which is lean in both banks according to my book that came with my old ass Superchips programmer, ha. All these years I was told that I had 3 out of 4 bad O2s, so I just go with it & call my friend at BatoZone to set me out all 4 sensors & he tells me that it's prolly my MAF. I told him it would've thrown its own code, if that were the case. I asked if the regulator could be at fault & he then said it could be my fuelpump. I told him I'd just replaced it last year. He says I need to check my pressure, so I do that today & at idle its around 43-46#s & when I rev it, it jumps to 50-55#s.

I'm not exactly sure, but I thought I just read something on here lastnight about most all the GEN 3 truck motors were running around 59#s.
I'd like to think it's something simple & fuel related since it really got better when I swapped the filter. Jeez ol' Pete, I mean hell, I have 267xxx on this bad gurl & drive the living shit out of hermost every chance I get.

Which is why I'm trying to get this other motor built to relieve the original, although she's still strong & willing. I would like a good pinpoint before going out & buying all 4 O2s, hi-flows cats or ORY. Or another pump or regulator. It prolly wouldn't hurt to have it scanned by a better scantool, also, ha.

Didn't mean to jack this thread either, BTW.