Intermittent Rough Idle LQ4

[Manita0909]

Hey guys, looking for some help finishing the troubleshooting of my stock '04 Silverado 2500 with ~230k mi. It's 2wd and has the 6.0 LQ4 iron block with 4L80E trans. It's experiencing what seems like an intermittent misfire at idle only when warmed up. I can only get it to occur if I drive for at least 10min and stop in drive (like at a stop light). Then at random a cylinder seems to miss for 1-2 seconds. As soon as I accelerate from the stop there's no discernable misfire. With a pocket scan tool I could see the ST and LT fuel trims stay under 8 on B1 and 5 on B2 before, during, and after the event. No codes are being set. 

 

When I bought this truck a couple years ago, I took on a bit of a project getting it running right again. Since I bought it I replaced:

-The Plugs/Wires/Coils (worn or had too much resistance)

-B1 and B2 02 sensors (originals were no longer capable of producing a consistent voltage pattern.)

-Engine coolant temp sensor (innacurate)

-MAF sensor (Low voltage and wouldn't improve with cleaning anymore)

-Knock Sensors (both gave low voltage readings)

-Intake manifold gasket (w/ knock sensors)

-Exhaust manifold gaskets (exhaust leak)

-Cam position sensor (rough idle after startup)

-Crank position sensor (hard starting) 

-Fuel pump (original whined its way to death about 3k mi ago)

-Fuel injector rebuild

 

The truck was running great after I did the work above. It's only developed this intermittent misfire over the last 2k miles. It seems to be progressing but I'm having trouble figuring out where to start diagnosis in this one. I already checked for vacuum leaks, fuel injector performance, and bad grounds. I'm not a trained mechanic, but I'm handy with a wrench and a Fluke.

 

Any wisdom or insight would be appreciated. Thanks