http://www.c-speedracing.com/faq/06.php for checking the code.

http://www.c-speedracing.com/faq/05.php for determining what the code is.

There is nothing we can do to help you unless we know what the code is. I believe when the CEL flashes, it is alerting you that there is damage being done to the emissions system, so get the code ASAP before you have to buy a new cat.