Yes, the OBD1 systems have less codes, and less data to look at. I had hoped you would have been lucky, but as suspected, the MAF did not fix the issue. As for the check engine light not coming on when you disconnected different sensors: The older systems had less strictness to the requirements to set a code. Some codes will not set unless the failure is present for 2 consecutive engine starts, and some codes do not test for actual connection of the sensor. Hopefully the new tech you are taking it to will be able to find the problem quickly.