Of course, I do feel a responsibility of saying "never diagnose yourself", so there I said it.
That being said, I do understand that the ENFP, given certain environmental factors, could possibly become a BPD. I think we are manic by nature. If you do feel like this is an issue and you are struggling to maintain normalcy in life/ relationships/ etc., there is no harm in talking to a professional.
I don't have BPD, but I have wondered if I have cyclothymic disorder. It's a mild form of bipolar disorder, in which you go up and down with mania and depression but not to a severe degree. While sharing certain traits, bipolar and BPD are very different in origin. Bipolar disorder is mainly due to chemical imbalances and BPD is usually an environmental influence. I go through bouts of high energy, excessive talking, no sleeping, complete joy or extreme irritation, jumping around from idea to idea, needing to physically keep moving for days and days, if not weeks. Usually I come down to stability, and rarely I go through bouts of depression.
I solve this a variety of ways. I am on a thyroid medication that raises my energy, so sometimes I take a break from it for a couple days. Eating nutrient rich foods and getting daily exercise also helps. I avoid junk food and processed sugar. In addition, I take fish oil twice daily because it is an anti-inflammatory that helps regulate mood sings. If I can't sleep, I take a sleep aid.
Have you ever watched "Girl, Interrupted"? Winona's character exhibits signs of BPD.
Also, here's a useful link:
Differentiating Borderline Personality Disorder from Bipolar Disorder | Psych Central Professional
Hope any of this helps!