1992 240SX Nissan (standard transmission) ignition problem

I have replaced:

-battery cables and ensured proper ground

-starter motor (had it tested before installation)

-the ignition switch assembly (got a new key and everything)

-starter/ignition relay switch

and tested the battery, yet the the engine still turns only about 20% of the time when I try to start the car. Aside from replacing the clutch relays, (meaning spending more money) does anyone have any other suggestions?

Need more details on how it fails to start. Does the starter run, ie the engine crank? if not, do you get a click when you turn the key? Do the dash lights come on?

You forgot one thing: Why do you think you have an ignition problem?