I read an article in the past year about those instances in which it is undesirable to use "if I were." There was an explanation that the subjunctive would be used in cases in which the speaker is speaking of improbability, but in other cases in which the action was probable or complete, the subjunctive should not be used. Interesting. Apparently I had over-learned the principle because I always favored 'if I were'; now my choice is filled with doubt and trepidation. Not really, but I do choose with care.

"If I was, in fact, in error, I wouldn't be standing here at this instant."

"If I were a millipede, my shoe bill would be through the roof."

But there are so many other applications of the subjective that go far beyond the 'if I were' construction.