Corrected caps (the ones with all left side wires coming out the left side of the cap, etc.) are junk in my opinion. I had one numerous years ago, and it gave the same symptoms you are experiencing. I replaced it thinking I got a defective one, and it did it again. As soon as I replaced the distributor cap (and new wires, of course), the problem went away. I haven't spoken to anyone that has had good luck with those distributor caps.