89 245, LH 2.4, Auto, 140k

Symptoms: I posted recently that I installed a new O2 sensor (Bosch 13034) and that I noticed this VERY sharp drop in gas mileage per tank. From almost 300 to barely 150. I put in 7 gallons on Saturday and have got about 70 miles and I'm about out again. The tailpipe is suddenly blowing pretty black, has collected a ton of carbon deposits and had been nice and clean before this. The RPMs seem to fluctuate only slightly, but the engine is running very rough. It seems to cruise ok and accelerate fairly normaly, but is SUCKING gas.

Here's what I've done so far:
First off- I am not leaking gas anywhere, both fuel pumps work, I have not had gas siphoned.
1)Like a jacka$$, I threw away the old sensor after putting in the new. Enough said.
2)While the car is running, I've unplugged the new sensor black lead and double whites and there seems to be no noticeable difference at all in the engine running.
3)I have unplugged each fuel injector one at a time and have noticed a harsh engine running condition with each.
4)Diagnostic Control Function 1: I pulled the codes
1-1-3 "Fault in fuel injectors,"
2-2-1 "Fuel system compensating for extremely rich or extremely lean air/fuel
mixture at cruise
2-3-1 "Fuel system compensating for rich or lean air/fuel mixture at cruise"
5)The "Check Engine" light has never gone on, but it never has and is probably a bulb burnt out.
6) Diag. Control Function #2: everything seemed to check out fine.
7) Diag. Conrol Fucntion #3: The system cycled through the air control valve successfully, then the injectors, 3 TIMES each. Valve-inject-Valve-inject-valve-inject.
To me, it felt like all 4 injectors were pulsing and clicking simultaneously.

I'm not handy with a volt/ohmeter. I do have a multimeter that measures ac/dc voltage, resistance and dc amperage.

Where/what should I look at next?
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89 245 'loaded' with a Great Pyrenees; 91 245 project