I would delete (using the edit function, not manual delete in microscope mode) *all* data in your tracks that you did not intentionally enter yourself, especially stuff like (as you found) pitch bend, any CCs (like mod or something) if you didn't intend them to be there, and especially Poly Aft and Channel Aft, which are real easy to enter inadvertently. Delete *all* of that stuff and see how your memory looks then.