I use to have awful cystic acne too so as you can imagine my face has been left with these permanet red marks (and a few holes).
What our makrs are called exactly is post inflammatory hyperpigmentation ...visit this website
http://www.acne.org/messageboard/forums.html
Scroll down to hyperpigmentation, its far down (i dont run it but im a member of the message board) i've been trying some of the things they reccommend (like lemon juice, apple cider viengar) but the best method seems to be using retin A or something like that (forget how to spell it) but i heard ot costs alot of money... Alot of people on that site list what they have had success with so its worth a shot to look around.
Hope I helped, best wishes!