91 s13 ka24de [please help me:(]auto to manual swap running REALLY rich
 

Hey guys, first post here, but I have a 91 s13 ka24de, (auto to manual swap), and my car is running really rich. Fouling plugs out in less then 5 minutes of driving. Need help to trouble shoot this problem. My teacher at school has a obd1 snap on scanner, it was reading 5.12 volts at idle-WOT, unplug it, and it's cuts to 0'00 volts.( this is before I swapped harnesses).What I've done so far(I work at O'Reillys, so I can try it and return it if it didn't help):
6 different a1 cardone MAF's. (Currently running oem maf because it's working the same as the remanned)
Coolant temp sensor.
All 4 injectors (new).
Replaced/cleaned/added grounds.
Spark plugs(like 10 sets, cause it's that rich).
Plug wires.
Replaced the engine harness with an uncut manual harness.
Tried 3 different ecu's including mine.
New cap and rotor.
Replaced the egi and egi pump relay.
Compression checked #1:105, #2:110, #3:115, #4:118.

I really need help because I don't know what else to do. Have checked every single thread on every forum about this and nothing that fixed their problem helped me. (Will add more as I remember.)

Try replacing your O2 sensor and make sure your air filter is clean

Already replaced the o2 and the filter is clean. Didn't change at all.

you have an adjustable fuel pressure reg?

Just the OE Nissan one that came with the block.
I was thinking about getting one but I can't afford to keep spending all my money on something that might work.

*also got it scanned by a snap on scanner and the maf read 5.12 volts plugged in. Unplugged it goes to 0.00volts. Swapped the whole harness and it's still doing the same thing.