I have a 2002 Pontiac Aztek with about 170,000 miles on it. About 3 weeks ago, it began having problems when I would hit the gas to speed up. It would hesitate, and then jerk forward and go. Then about 2 weeks ago, I was driving on the highway and the engine just suddenly stopped - as if I had turned off the key. There was no warning, no sound, nothing. I kept hitting the gas the whole time and it started up again after a minute. I replaced the fuel filter and it ran well for a week. Then it happened again, but this time the engine completely turned off and I had to turn the key to restart the engine. The engine started with no problem. I tried to drive to the mechanic, but the engine stopped & started again on the way, so I ended up having it towed. It is not driving roughly or idling roughly, it doesn’t make any strange sounds and no warning lights come on. When the engine stops, all electrical components are still working (lights, radio, etc.). My mechanic appears to be stumped. What could be causing this?
When an engine does that it is either not getting enough gas or the ignition is malfunctioning. Your mechanic should be able to find the problem. Often sensors malfunction and you do not get tge proper air/fuel mixture in the engine.
Have your mechanic check for a defective crankshaft position sensor. This sensor tells the computer whether the engine rotating or not. If the computer loses the signal from this sensor it thinks the engine is no longer rotating so it shuts down the fuel and ignition systems and the engine shuts down.
Tester
Another possibility is a fuel pump dying. This can also occur intermittently with the pump being fine for a random amount of time or miles and abruptly quitting; only to have to engine start back up and run fine again until the next episode.
That’s just a random guess too because not enough is known about any process your mechanic has gone through with this vehicle.
Check the pipe running to the egr solinoid on the back of the intake. It can get pinched and after a mile or so kills the car. It will start right up but only run for a bit then die again
Welcome to the forum…
But I don’t think after 12 years the OP is still having this issue… lol
If you are here to help out with car issues, it would be better to pick some more current events then from 12 years ago… Like in the last few days, there are a lot of them to choose from…
Well i just saw the post and figured i say my experience that happened.
@SD4kaerials_187436 experience probably won’t help the OP, but other’s here finding this thread using the forum search might benefit. Worse case, no harm done.
it is an Aztec. Chances are pretty good it is still not running…
That was my 1st thought, but I decided against it… 
Maybe the Aztek saw itself in the mirror. That would cause it to suddenly stop.