P0143 is related to bank 1's rear oxygen sensor. See:
Porsche P0143 OBD/DLC Error Code - O2 Sensor Circuit Low Voltage.
Did the replacement sensors have integrated plugs or did you have to splice in plugs? If you spliced them, you might look at your connections again. If not, did you keep the old ones. If one of old rear sensors was OK, you might put it back in, clear the code and see if it stays away. If it does, the new sensor is bad. Or you could swap the new rear sensors from side to side and see if you get a bank 2 code. I'm not sure what to suggest other than cleaning the MAF and see if that clears up the problem.
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