You sound biased or your information is incorrect. Rigging elections and politics by ISI was started by Bhutto by creating its political wing which is still in existence.
As far as the independence ISI gained during and after Afhgan war is concerned, Musharraf took care of that and brought it under army’s control. This fact has been mentioned by some foreign analysts.
Now there is nothing different ISI does that an intelligence agency is not supposed to do. I would say they are much more ethical and professional than RAW and obviously much more than CIA.