Could also easily be a bad ECU. The factory ECU in my 90 Legacy loaner car went bad and threw about 6 codes we could never clear. Swapped that junk for a LINK plug and play and the LINK had no issue at all with the wiring or sensors - car ran flawlessly. That was the era where they started pulling the lead out of the solder and it cracks with age. Not to mention leaking capacitors, etc. 

It may simply be a bad computer. Best way to deal with that is to round-file the stock ECU and run it with something like the LINK Monsoon. 

https://dealers.linkecu.com/G4X-MonsoonX-ECU-V3

GD

I decided to re-verify my MAF harness voltages.  It's getting 12V on the red wire, but the white is reading 5.3 mV (key on/eng off).  Specs I've read are 100-500 mV.  I am thinking this is not bueno.

Where is the other end of that white wire?

Edited August 28, 20214 yr by Phil Hyde

my chilton manual says white wire is the signal wire - I presume it goes straight back to computer.