Car cutting off?

This problem just started yesterday. My service engine light is on but have had this problem for quite some time. I get it fixed and it eventually comes back on. Yesterday when I was driving my car it just cut off while accelerating. I pulled over to the side of the rode and it started like nothing was wrong. Drove it a few times yesterday and didnt happen again. Well was driving today again accelerating and the same thing. I pulled over to the side and it started right back up. Any ideas? Hasn't happened but twice but im sure it will happen again, and hasn't happened while im stoped. Both times I was accelerating