Power Steering Failed problems of the 2013 Dodge Grand Caravan

Car stalls unexpectedly while driving. The engine stops and there is a complete loss of power. Power steering fails and it is difficult to manouver vehicle. I can successfully restart the vehicle by either stopping the car, shifting into park, and restarting by turning the key, or shifting into neutral while the car is still in motion, then turning the key to restart, and then shifting back into drive. This has happened at least 10 times on the freeway going at freeway speeds over the past year, and dmore than 50 times on surface streets. Often this happens when hitting a bump in the road, but sometimes there isn't an obvious cause. Once while driving on a bumpy dirt road it repeatedly stalled, but when I held the key in place, it stopped stalling. We had the dealer look at it and they couldn't find any problems. We replaced the key thinking that might help, and it seemed to for a few months, but now the problem is worse than ever, stalling at least several times a week. In the past several months the car almost always won't start on the initial key turn. I have to hold it in start position for several seconds longer than normal, and I have to give it some gas and rev the engine for it to start. Having the car stall at any point while driving is frightening, but when this has happened on the highway, it is terrifying and horribly dangerous for me, my family, and other vehicles around me.