car dies

my car dies it seems like after the same distance each time and wont start again. but it will start right up an hour or two later. somebody told me it was the oxygen sensor but i just wanted a second opinion. by the way it is a 91 chevy lumina z34

Not likely.

I'd be suspecting something electrical, that open-circuits when warm. How long do you have to run it before it dies? How does it run otherwise? Rough? Poor power? Runs fine until it dies? Will it run until you idle the engine, then die, or does it die no matter how fast the engine is turning?

I would suspect an ignition module. As they tend to work fine when cool, fail when warm, and then work fine again when they cool off again. You can rip it out easily. Its under all the coil packs, you should be able to take the whole assembly to a place like autozone and have it tested for free. If it tests good, a crank position sensor will also cause the above problem. good luck.