Why does my car turn off?

I have a 2000 Ford escort zx2. What happens is that when I have my car on Park I turn the steering wheel all the way till you can't turn it no more and it turns off by itself. My car shakes every time I turn the steering wheel (left and right) when on Park. I know it shakes because the engine mounts aren't that good but why does it want to turn off?

If that car is equipped with a Power Steering Pressure Switch (PSPS) and I *think* it is. I would guess that it might be disconnected.
The PSPS is used as an input to the PCM so that the load of the Power Steering on the engine (at idle) can be compensated for by boosting idle speed a tad bit.
It's on the high pressure side of the system, usually on the hose, sometimes on the rack.
I'd be willing to bet you find the connector off and just dangling in the breeze…