Hyundai Repair: 99hyunda elentra, crankshaft position sensor, engine cranks

Question
the car runs but either it shuts off or i turn it off it will not start right back up it takes about 10 -15 minutes before it starts up

Answer
My immediate suspicion is that you may have a faulty crankshaft position sensor.  These often fail when the engine is warm and then work again once it cools.  Typically, it will also cause the check engine lamp to come on with a diagnostic trouble code P0335.

I'm making the assumption that the engine cranks but does not start when the problem occurs.  If this is not the case, the crankshaft position sensor is not the issue.

I'm also making the assumption that since you haven't mentioned it, there is no significant lack of power leading up to stalling out.  If there is a lack of power leading up to the stalling, especially if it's worse the farther the accelerator is depressed, I'd suspect a fuel pump issue.

Keep in mind, however, that these are just educated guesses based on common failures and the symptoms typically associated with them.  There are a host of items that can make your car stall and not restart.  Ultimately, if you'd like to make a concrete determination, testing will be required.