Nissan240sxrb25det

Ok guys I rebuild an rb25det put all new parts CP piston, eagle rods, metal heagasket, new water and oil pump, new coil set, timing belt all new gastets etc. the engine ran great for the first two weeks and 200 miles. I changed the oil evey 100 miles since it's newlly built. Yesterday I drove to work as I stop at a stop sign it died. no smoke no noice just died and it won't start. It is not the starter or the battery is all new. the motor turns fine, there is a popping noice on the first turn of the key comming of the Exhaust or Esternal Wastegate under the car. I also check fuel and it seems it is getting plenty, check all the fueses no blown fuses. I have been real careful not to go over 4000rpms until I get it tune. Does any one have any idea what the issue could be.