Q: Recurring dropped coils in a 2006 Avalon w 66000 miles !!??

There is no history of premature failure of Toyota OEM coils in this application. Aftermarket coils might be a different story, though. A typical cause of coil failure is faulty spark plugs that create a high resistance (or faulty wires but you have a coil on plug system). Lean operation can be a contributing factor as well. The latter can be ruled in or out using an automotive scope. Are you using Toyota OEM replacements? If not, that can be an issue in terms of the quality of the aftermarket unit you might be using. If you would like the required diagnostic steps performed to get this resolved, please request service and a certified mechanic will perform the required work right at your location. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.