2003 Daewoo Kalos Stalling and loss of streering

My husband was travelling normally, stopped at lights, when he tried to accelerate the ngine cut out and he lost the ability to steer. A friend whi is a mechanic checked the car, said he could find nothing wrong but drove the car home to assess its performance. Twenty minutes into the journey it did it again. He said he doesn't knoe what is wrong and said we need to have a computer diagnostic performed on it. My husband and I are both students and cant afford to have it done but we need the car for medical reasons as well as for work. Any suggestions