I have codes P0420 and P0455 plus random misfires. How can i fix this

Hello Lee If you could bring it to our shop in Wichita, we would start with a induction clean, using B/G products. This job takes about 1hr of labor and a 10 mile test drive, cost it be under $200 (What the problem is the exhaust converter is dirty) most of the time we can clean it will take care of the code, if it does not the converter will need replaced, if we could help please let us know Mark JOY mark@joysservicecenter.com (JOY'S SERVICE CENTER)