Engine cuts off while driving. Service engine light on.

I have an infiniti QX4 2001 thats regularly serviced. For some reason its been cutting cutting off almost like the fuel is not getting where its not getting to. But shortly after it will start up again and drive like it's 100% fine. Pep boys diagnosed it and an erros code came up with the IAC but thats new and so is the computer. They also suggested it could be a probelm with the vaccum in teh air hose but they couldnt quite get to it to make sure. I took it to the infiniti dealer and they said the codes for teh IAC had o be relearned. It thne drove fine on a 2hr trip back to my area and then as I slowed down to it cut off again and this morning cut off thrice. But before the tow truck could get there it started up and drove smoothly back to my house where Im trying to figure out this problem.