Latest update, I did get the first dealer to start up a new truck next to my 3,200mi truck and of course the new one didnt have the noise. I picked up the truck took it to another dealer who said the same thing. Referred me back to a bulletin PIP5606 explaining the engineers are working on figuring out the cause of the problem and a solution. Seeing how the first release of this bulletin was in October 2018 stating they are working on a solution, i don't think the engineers are in any hurry to find the problem. The bulletin was also updated 2 weeks ago to include all 2019 V8's. GM corporate said they understand my frustration but will not work with me towards a buyback, exchange, or engine replacement. My feeling of the attitude was it's your problem now, nothing we can do about it, quit calling.
My plan of action is continue talking to lemon law lawyers, file complaint with BBB, file complaint with consumer rights groups, have some magnets made for the truck and park outside various Chevy dealers with a bull horn to warn people on the lot not to buy. The first time I did that they got pissed! Other courses of action will include contacting local media with my hours of recorded conversations with GM service and mechanics agreeing that its not normal. I can't rule out taking my magnets and bull horn right up to GM corporate headquarters in MI. Maybe some folks would like to join me.