kenh
I see nothing I hear nothing
Its just a grounding problem.
Or at least you cant diagnose it untill you check out all of the grounds.
Take a look at the ground strap from the back of the passenger head to the firewall.
It shares a common lug with a strap that goes to the frame.
A real ***** to get at which is why they never get checked.
Your ecm and sensors have a ground to a stud right next to the manifold temp sensor.
check those out, not with a meter, continuity doesnt mean **** of of the meter.
Pull them all apart, clean em up put new good quality heat shrink connectors on.
The starter grounds to the block, the block has a few grounds but they ground in different "planes"
In other words those grounds are providing a path for different sources.
If you are missing a ground or have a weak or intermittant ground, The path then goes through whatever other ground it can find.
It just wants to go back home.
If you have no grounds, it will go through the transmission cable or the throttle cable or even the main bearings or the transmission.
So, before you go too nutty brother.
You cant diagnose a gm tbi unless all of the grounds and power are good and solid.
Crawl up and under and all over it and fix all of that every damn bit of it.
Live data does not mean **** all of anything if it is from an ungrounded or intermittantly grounded systen.
^^^^^^^^^^^ YES!!
ALL vehicles since the invention of the computer are much more sensitive to grounds that pre computer. Flaky grounds cause more issues than you can imagine!!! Like I mentioned before, after I cleaned all my grounds my intermittent hot start issue disappeared. I used a scotch bright pad on my die grinder to clean the block and firewall connections and any other ground point. The engine seems to run better/smoother. That is as long as the ICM works. LOL
BITE THE BULLET and clean the grounds (includes dropping the starter and cleaning the block) and then see where that takes you.
Ken