Raptor 660 CDI problems?

I have piped raptor 660 with no lid, and i have a performance CDI which i have to run because my other two stock cdi's will not work properly. Im just wondering if the stock cdi is the problem. When ever i have the performance in, it starts fine and runs fine. When i have my stock one in. It starts fine at first then it slowly get harder to start, and then it will start making a clanking noise and is very hard to start, unless i hold the throttle 1/4 at the same time i start, but one i do get it started, it runs fine. it intermitting. anyone know.