13 veloster stalling issue, intermittent, no codes

Hi. Im working on a 2013 veloster 1.6 4L turbo 6speed manual. Customer drove to work and says she left idle on arrival for 5-10 min car stalled and would not crank after. I arrived about an hour later and car crunk, ran normally, no codes and no drivability issues. Left it idle about 15 min and nothing. She decided to take vehicle home and same problem happened. I picked up the car at her house and drove to the shop let it idle for 30 min until it finally stalled out at idle. Code p0087 came on pending low fuel pressure on rail. But car crunk back up code went away by itself and has not done the stall again after leaving idle for about an hour checking regularly. Any ideas on where i can start testing? Im suspecting a bad crank sensor and will test the signal today but being that it rakes so long for the car to fail i dont know that a cranking signal test will give me the answer 

you could check fuel pressure ,and that your throttle plate in clean / filter, tuned ,iac valve, did you check freeze frame ? good luck

I have seen intermittent failing crank sensors on that engine before causing hard to duplicate stalls, but they are usually not accompanied with fuel pressure codes

CURIOUS IF YOU FOUND THE PROBLEM? I WOULD SUGGEST LOOKING INTO THE TROUBLE CODE FOR THAT SUSPECTED AREA, WETHER ITS FUEL SYSTEM OR ELETRICAL RELATED. I WAS TOLD ABOUT AN EASY WAY TO TEST FUEL PUMP IS PUT AND JUMPER WIRE ON THE RELAY SIDE AND TEST THE AMPS OF THE FUEL PUMP, IF ITS OVER 7.5 AMPS THEN MOST LIKELY NEEEDS REPLACEMENT. I HAVE NOT TRIED THIS METHOD YET BUT MAYBE SOMEONE ELSE HAS TO VERIFY IT

Thanks everyone for your help i ended up driving it for 30 min and parking it to wait for the stall. While recording the data with my scanner. When it started to fail i blipped the gas pedal and saw that it would go back to normal for a minute and then mees up again. 

i removed the in tank fuel pump and saw the fuel filter and strainer had seen better days and there was an in tank fuel pressure regulator there as well so i swapped the fuel pump assembly since it was less expensive than getting all 3. I can’t confirm it with a test it is just a hunch because it would keep working when you blipped the throttle but i believe it was the fuel pressure regulator. I kept it to try and figure out how i can test it later and the fuel pump itself is good so il going to clean it and use it for an irrigation project

I tested the car and all is good.