Never mind - I figured it out...
lol, that's what someone else did here, couldn't believe they didn't share the solution with the rest of us!
First of all, CHECK ALL YOUR GROUNDS! I checked mine off the back of the ECM plugs while they were still plugged in, and they were all 0 resistance to ground(solid).
OK, but here's what it was. On the ECM, there is an orange wire that is supposed to have 12v battery voltage all the time(key off). When I checked it(multiple times!) I had 12v there, so I thought it was good. What I didn't do, is check it while I turned the key on or was cranking(putting a load on that circuit). I'm sure most people would not check it while cranking because that is when you would be checking the OTHER terminals that are supposed to be getting voltage at crank! I don't know where it is, but there is a connector, or split in the circuit somewhere that is part of the fuel pump relay/oil pressure switch/ECM-B fuse supply(according to Haynes book schematic), and when I would turn the key on, the 12v supply(to the ECM only!) would drop to about 1v...now - key OFF, it would show 12v, but when it needed to, it couldn't supply any current! There is a bad connection somewhere that would basically go open when any current was needed - this is why I had flaky ref voltage to my sensors(it was different every day it seemed), I had no check engine light(self check when key is on), AND ALSO, no injector pulse! I'm thinking whatever grounds the injectors needs 12v to operate properly...now, even though I had only 1v to the ECM at that moment, there was still a solid 12v to the other devices on that circuit(fuel pump relay, oil pressure switch etc...the ONLY device on that circuit not getting a solid 12v was the ECM...I feel a little proud that I figured this out(a new ECM like so many have done wouldn't have made a bit of difference) - I hope this helps someone else out...I also found another possible future problem while changing my blower motor. You need to take off the pass side kick panel to loosen up the dash, and when I did, I found a bundle of wires and multiple connectors(all factory) that sit in a hole behind the kick panel, the largest connector has 8 wires that go to it...the GM engineers, IN THEIR INFINITE WISDOM, have this large connector sitting at the bottom of that hole on top of some of that factory foam filler crap that obviously gets nice and wet everytime it rains...or car wash, or you name it...the corrosion on my connector was incredible to me, because all the connections were still working! Needless to say, I cut the wires, soldered, and sealed them, along with wire tying them up off the bottom of this cavity...I'm done......again, I hope this book I just wrote helps someone out! lol-Troy