car shuts it's self off
 

I have an 87 camaro with an ls1 conversion, that has been running fine for over a year, but for the last month the car has been shutting it's self off. it seems to only do it when the engine is warmed up, it will randomly shut off while i am driving it and even when it is idling. does any body have any ideas of what could be the problem.

Is there any body that could point me in the right direction? I put it on the scanner the other day and there where no codes that i could see relating to this problem. just a few evap emission codes, because i don't have any of that on my car. the codes were
po418: secondary air injection system a malfunction relay
po449: evap emission control system vent
po452: evap emission control system pressure sensor low

could this maybe be a feul pump problem? I'm not sure because the car dose not seem to struggle before it stalls. the engine just seems to cut out, but all the electronics stay running.