my check engine light is blinking and my car is running very sluggish

It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online What trouble codes are stored P0420 is a bad cat. converter but the question is what caused the cat to fail, that needs to be addressed or the new cat will quickly fail.