It's normal to loose power steering when the enging stalls because the engine isn't tuning the PS pump. The key is still in the "on" postion so the radio still gets power. A low or rough idle could be caused by intake hose leaks. The cat could be a problem but would also cause lost power at mid-upper RPMs and some strange exhaust/intake noises. CELs, overheating, and a hot footwell area are other extreme symptoms.
