Early '90's ECM ground wire location???

[90rocz]

I'm getting all of these weird readouts like:
coolant temp=(-38.6*)
air temp=(-14.8*)
TPS voltage=(4.70v @ idle!)
throttle position=(0%)
02's=(435vm)
spark advance=(0*)
knock count =(0,even after revving)
quad A=(low)
quad B= (low)
loop status=(open, even after 5min.)

***Then while I'm still watching, in "real-time monitor mode"(Auto X-Ray) it suddenly smothes out, and ALL OF THE READINGS RETURN TO NORMAL!!???**(and then vise-versa...)

That's why I believe a loose connection exists, anyone have some input?
I hate intermittent electrical problems

 

[90rocz]

FYI:
I found the problem, after doing a running "wiggle-test". When I gently tapped on the ECM box, the car stumbled and stalled 3 different times. So, I guess I'll be purchasing a new ECM.
thanks anyways...