Keep in mind that you cannot always relay 100% on drive cycle behavior to clear readiness codes in a few short miles.
It seems that in some instances that I have found if you have had codes for a LONG time, the readiness codes that may be associated with these codes may take longer to clear?? I have not seen written proof if this, however, I have seen first hand this behavior.
Need to know what readiness codes you have that are still not clear.
Also some codes need multiple cold start drive cycles to clear.
Evap codes are usually the last and hardest to get clear.
Also you should read the first 2 links below in my signature. It probably has info on many of the most common problems that occur.
Also keep in mind that some states allow up to 2 readiness codes to not be clear and the car can still pass if there are no CEL codes.
But you need to find this info and fully understand what the rules are for your state.