Power Steering Failed problems of the 2008 Kia Motor Sedona

For the first incident, while coming to a stop sign, my son was driving the vehicle stalled and the ignition powered off, power steering failed, brake and battery lights came on and quickly the power came back on though the power steering still failed. Van had to be shut off and restarted for power steering to resume. This was first happening very infrequently but is now happening more, usually when coming to a stop but has also happened at steady speeds - 35mph, 20 mph, 5 mph. It usually happens in very heavy rains/wet conditions but has also happened once or twice in dry conditions. In addition: *passenger blinker will stop working for a week or two then randomly start working again (this pattern continues). The bulb has been replaced but it continues to happen. *passenger side door locks do not respond to key faub or power locks and have to be locked/unlocked manually. *passenger door randomly will not open from the inside or out. Cigarette lighter no longer works. I believe this is all related to the electrical system with the biggest obvious concern of the vehicle's power out and loss of steering. Clearly, this can cause a major accident. Mechanic was unable to reproduce the engine stall issue.