car stops when hot.

So, Friday I was driving my 2003 325i home from the lake. I was going about 65 on the interstate and my car lost all power. I pulled over and put it in park at which point the battery light and oil light illuminated red and went off. I turned the car off, took the key out, put it back in and restarted. It acted like it was going to run fine, then did the same thing again. Long story short, it got to where it was very loud puttering and died when I put it in gear. I had it towed home to a local mechanic, where it didn't act up for a while. No codes. Nothing. Later today, after it had been running awhile it finally died. He cranked it back, it ran for a minute and died again. He still has to put code readers back on it but. Any ideas?