1992 Chevy Lumina I need my car

Hello, I am trying to figure out what is wrong with my vehicle and I was really hoping that you guys could help me out since I cannot find anyone who can. I have had my car for about six months and it broke down a month and a half ago. When it broke down I was on the interstate and I heard a clicking noise when I stepped on the accelerator, and shortly after that the car turned off completely. I called a friend and luckily my friend owns a mechanic shop and he came and by the time he got there half and hour had already gone by. The really strange part about my car is that it started! We thought it was fine and I kept driving on the interstate trying to get home. Three miles ahead the exact same thing happened, same clicking noise and of course the car turned off. I got a ride home and my friend towed my car to his shop. The car was at the shop for a month and my friend had many conclusion about what might be wrong with it. He thought it was the gas pump and he replaced it; it wasn't that. He replaced the coils: it wasn't the coils. He later said that he had made a few adjustments and that the car was ready to go and that it was working perfectly. I went and picked it up, where it was which is about 45 minutes away. The car made it home fine but two days later when I drove it on the interstate the car broke down. The car did the exact same thing! The same clicking noise and the same type of turning off. I don't think it is something that will be too bad because the car runs very good and when it turns off, if you let it rest about an hour it will turn back on and keep running for awhile. What can be wrong? The car turns on that is what is appalling to me. I really hope you can help. Thank you, I will be waiting for your answer.