Start off by checking to be sure that all the connectors were reconnected properly. Clean the battery cables on both ends, including removing the boots on the battery end and cleaning there. We've had many strange issues be caused by poor, corroded connections. Also, check the wiring for all the sensors that show up as a problem. It almost sounds as if one of them could have grounded itself someplace, and then dropping the voltage to the other sensors, making it appear as if they're all bad.
Another place to check is the grounding busses on each side by the front foot wells.
Black 2000 SSEi, Silverstar Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, drilled 180 degree thermostat, Intense FWI, PCM, shift kit, and 3.4 Pulley. Solid front mount.