modal verbs - If something was vs If something were

If I were an MLA, I would have helped people yesterday
If I were an MLA, I would help people tomorrow

If I was an MLA, I would have helped people yesterday
If I was an MLA, I would help people tomorrow

Are they grammatically correct? Someone says If-something-was and Perfect tense' (would+verb third form) aren't acceptable in condition sentence to use along with one another. They say If we use them with perfect one, then it will be correct. For example: If I had been an MLA, I would have helped people. If I were/was an MLA, I would help people Are they right that that's incorrect to use so? I'm oblivious to the examples because I haven't influential skills on grammar; I wrote them on my own. Sorry If I made any errors there

Answer

"Were" is US usage, "was" is Commonwealth.

If I were an MLA, I would have helped people yesterday

Doesn't work because "were" is talking about today. It would have to be "if I had been an MLA, I would have...."

If I were an MLA, I would help people tomorrow

Okay, albeit odd-sounding, perhaps because of the specificity. Less-odd would be "if I were an MLA, I'd actively help people" [no time specified, indefinite future implied]

If I was an MLA, I would have helped people yesterday

Same problem as with "were", but Commonwealth. "If I had been...."

If I was an MLA, I would help people tomorrow

Same response as with "were": is okay, sounds odd.