My friend owns a 1994 Altima, and it has started randomly dying on her while driving. When it happens it's roughly 15 minutes into driving, it will start chugging then die. Sometimes it will start back up, sometimes it won't. On occasion it flat out won't turn over. She replaced the fuel pump before she came to me thinking that was the problem, but that didn't fix it. As far as I know everything else is kosher, no CEL or Oil Pressure light coming on. Some days it doesn't have a problem at all. My initial thought was Crank Position Sensor, but as far as I know they didn't start putting those in Altima's until 1995, right? Anybody else run across a similar problem?

When this car dies, do you smell gasoline in the exhaust? Other cars I have worked on refused to start when hot due to thermostat problems but could be easily restarted cold.
The 15 minute time frame reminded me of this, because it takes about 5-10 minutes for my Altima to fully warm up.

No gas smell that she can remember, it hasn't happened in the last few days though. She also says her temp gauge goes up normally when it warms up. What would be the right way to test the thermostat to confirm or debunk any issues with it?

On My Altima there are two thermostats, one, a mechanical valve that allows coolant to flow to the radiator and another, an electrical sensor near the upper radiator hose that operates the gauge on the dash. The coolant thermosat should not cause the engine to die, even if it were malfunctioning. you can test it in the car by feeling the upper radiator hose to see if it gets hot when the dash gauge is about 1/3 up from cold. The thermostat opens around 170F. However, I was thinking more on the lines of an electrical problem.
When the car dies, you want to check for spark (a timing light or spark tester works for me) and fuel to the cylinders (smell the exhaust or use a fuel pressure gauge at the fuel injector rail). If both are present the mixture is off. But if fuel is not getting to the cylinders you have an ignition switch, fuel pressure, or injector issue.
One more Question: Does the car die at an idle when hot, or will it die while driving with your foot on the accelerator?