It is not a data port, it is an analog filter plus an amplifier, and an analog-to-digital converter.

Same part is used on the 2.8/3.1/3.4L P66 PCM's. You have a P6-style computer, but it's got P66 style programming. Not currently well studied-but you might start with the flash routines for the 94/95 OBD 1.5 computers used for the 3.4L V6 and LT1 V8 computers.