Joe, that was the defining element that pointed to my ECU problem. The dealer said that when the ECU goes, it will develop an internal ground loop which can give out many spurious signals that give false codes, as well as improper signals to the FI system. The resistance of the ground was not zero.
Other things that were a problem before were fixed after I replaced the ECU, like the up-shift indicator began to work again and an erratic and off calibration speedometer were miraculously fixed. The dealer said there was not any connection. Bahhh! I said!
The speedo gets it's signal from the ECU (not directly from the differential sender) and compares engine RPM to show the best shifting point for mpg economy on a manual 5-speed.