PS: did pinouts on diag connector - No codes!
And... I did a reach into the running engine with one of those "extension grabber things" to grab the sensor wires and wiggle them around a bit, and there wasn't any loose connections or bad connections (no stall), so no open or shorting wires down there anyway...

Sounds like you found the issue to me, you will need to replace your crank sensor.
I'd go with an AC Delco sensor, or if you have to go with another brand the Standard Motor Products brand sensors are not too bad, I personally prefer OE AC Delco or Delphi any time I replace any of my sensors.

I have never tried that .....I have "heard" stories of guys using a can of refrigerant and hose in the same manner, getting results like this, but never tried it.....

you could use anything that cools it, we have this stuff for electronics trouble shooting because thats what all electronics do when failing. it starts working cool and not hot so you spray it with freeze spray or canned air. they all just have refrigerants in them.

Duster (Canned Air) within Dusters & Freeze Sprays - MCM Electronics Category

Following up:
Got the Crank Sensor replaced OK, started up and ran fine, with occasional quick little "surges" lasting 1/4 second or so, then after it warmed up (20 sec past the "idle change") it died...
when trying to restart it acted like it had "jumped timimg" (hard cranking, engine getting stuck at top of compression strokes, chugging and occasional intake backfire)

Waited a little while and tried again, started with the same uneven idle, then died, and hard start symptoms as above...

Question:
When I removed the harmonic balancer I did not try to keep the flywheel or engine from turning, and also I had used an air impact gun...

Did I booger all my timing gears or chain up so now it "out of time" (which is why it acts like it is)"? (didn't know it might be important to secure the flywheel before removing the balancer, but found out after... didn't think an impact gun would hurt it just removing that bolt = it it turned the engine slightly, hey, isn't that what the timing chain does anyway?)

But I hear the original gears (cam, crank) might have been nylon or had nylon over aluminum or some such, and with would be easy to trash them and throw it out of sync...

Thoughts, anybody?

Much thanks for all help thus far, and your future replies!

the timing chain is metal you arent going to hurt it. not real sure about the sensor though, i have heard some need a crank relearn if its not the exact same as before. what brand sensor did you get? make sure there were no loose or corroded wires on the plug?

You won't hurt anything using an impact gun.....crank relearn is only for OBD II, I believe......

When you replaced the crank sensor, did you check the vanes on the back of the harmonic balancer for damage? Did you use the special tool to install the new crank sensor, for proper alignment?

Check the pins in the harness to the sensor that they are tight? Check harness wires for damage?

Hi (sorry for late reply),
Cam, crank, timing chain were all metal, as well as cam button end, so all that'* OK!

As to crank sensor - didn't use that special tool, but lined vanes up with slots so slight air gap on either side on vanes (vanes don't touch sensor)...
Vanes didn't appear to be damaged but were very dirty and so were cleaned up (solvent/degreaser, compressed air dried)
Fairly sure vanes don't hit sensor anywhere as now having it off after running briefly there is no wear anywhere on sensor "ridges"...

Will closely inspect wiring to sensor to verify "goode connexions"...

Thanks, will report findings soon

Oh, and the crank sensor brand was BWD (Borg-Warner?)

JUST found out BWD is Standard Motor Products, Inc.!!!