Thanks guys. Relearning the pcm and a new battery without a dead cell has helped the startup and idle issues but now I'm chasing a bad coil. No idea really what helped the original problem. Dirty connection maybe.
Why chasing? If You have a misfire the OBDII will call out exactly which cylinder(s) are missing, it will also count the exact number of misfires since the last time the data was
cleared/reset. One more thing to check is GM used ground terminal "gang buss" units attached to the underhood & other areas, which oxidation/corrosion renders the grounds
sub-par. I've cleaned these & occasionally had to move a terminal to a "blank" position if available to fix blower motors not running etc., anything attached is game.
