Multiple sensor issues

[99Silverado25006.0]

As the title says, I have multiple sensors that are throwing codes. The truck (99 silverado 2500, 6L) started bogging/choking when given more than half throttle and there was a really strong fuel smell in engine bay. Put a code reader on it (using universal odb2) and got "bank 2 lean condition" and a couple of bank 2 o2 faults. Upon inspection, i found a broken weld at the exhaust pipe flange. I fixed the weld, replaced the k&n air filter with a paper one and cleaned the MAF and throttle body. This fixed the choking issue but CEL came on again, when I checked for codes using the "OEM specific" setting, I got 41 faults! I won't list them all but each o2 sensor had multiple codes, heater fault, insufficient data, high voltage AND low voltage. Also got similar faults for ETC, knock sensors, EGR and TCC, amongst others. Aside from abysmal fuel economy (stays in open loop fuel mode despite normal engine temp of 100° C) the truck seems to run, drive and shift normally so I'm guessing it's a short(s) in the electrical system. Not very familiar with electrical systems so any insight would be greatly appreciated. 

[sefiroxx]

Search for critter damage. Start with the water temp sensor and go back (temp sensor is what triggers close loop).

[99Silverado25006.0]

Update-  The lean bank 2 DTC hasn't shown up since fixing the exhaust leak. As for all the sensor codes, I have checked all the wiring harnesses for damage and found none. Even checked underside of the fuse box. I put a voltmeter on all the sensor connections and they all read within .05 of 5 volts. From everything I researched, this is right where it should be. Could it be a faulty bcm or pcm? Should I even bother as driveabillity doesn't seem affected?