93prelude4wsh23

hey guys i have a 93 prelude 4ws H23 with 248k on it i just got it not to long ago and recently it has started sputtering and backfiring only at low rpms only when im trying to accel a little and its throwing the check engine light on reading code 43 which is fuel delivery. so i did a full tune up on it and changed the fuel filter and still no solution.
my question is could it be fuel injectors, fuel rail fuel pressure regulator or possibly fuel pump going out??
and is there ant way of testing these things?