E30 fuel pump relay. Engine spontaneously dies.

[CoxyNZ 2]

1988 E30. M20 motor. I opened up the relay box and have this-(pic attached). Some research online says the fuel pump relay should be in the center but there is not one installed. Trying to trouble shoot engine spontaneously dieing randomly when idling. (Happens about 1-2 times a week usually when stopped at traffic lights etc). What else could possibly cause this? Have replaced distributor rotor, cap, leads plugs etc so thinking fuel related. Any help appreciated cheers