Leakdown test will tell you something in any event..... How's your cat? (haven't read back thru the entire thread...)

Might be carbon buildup on the valves too. have you ran any seafoam thru the intake??

 

Cat is brand new; was replaced during the plenum fix as well as new o2's. Seafoam was run through the intake last year. It seemed to help with a smoother idle in general but it did not cure the hiccups the engine experiences during cold starts. The truck runs smooth and like a raped ape after the misfires clear up. And they clear up before the engine is at operating temperature (like after 5-10 seconds or the first application of throttle). Also, the truck doesn't do this every time (maybe in 2 out of 5 startups the misfire is noticeable). Its just rather annoying having to clear misfire codes every week...

 

Just for the heck of it decided to do resistance test on the ignition coil. Was suspect when i bought a few months ago because the middle part of it could be wiggled, it was loose. holding the ends of meter and moving back and forth gave readings from 11,390 to 11,330. Took it back for warranty. Made a heck of a difference in how smooth truck runs and the nasty ping is almost nil. Had been getting part throttle ping just driving around town. That's totally gone and just feels more responsive. The new coil was in the 10,000 for resistance. Would that be right for resistance spec's? The jumpiness at cold start usually would go away in a few mins, closed loop, for the most part. but sometimes feel it when going at idle speed or when had brake on, like pulling slowly into garage or parking. Will see what happens tomorrow.